!! !! Welcome to Unit Operation!!

!! 35 Year GATE questions (1990-2024), Year-wise and Topic-wise, and GATE Mock Tests with Solutions!!


www.unitoperation.com is a Complete Site for Graduate Aptitude Test in Engineering (GATE: Chemical Engineering, 1990-2024, arranged Year-Wise and Topic-Wise with detailed solutions), Government and Public Sector (PSU) Examination Question papers and Solutions, HYSYS and UniSim Simulations, Quiz, Job Interview and Professional Engineering (PE) Examination Questions, Study materials and Videos on concepts, , equipment and experiments. This is world's largest collection of Chemical Engineering questions and answers.  


1. Due to increasing costs of domain registration, domain hosting and other related technical and administrative activities, Single User Annual registration fee of Rs 1200 (US $15) for 1 (One) Year, Rs 2000 (US$ 25) for 2 (Two Years), and Rs 2700 (US$ 33) for 3 (Three Years) with unlimited logins during the registration period, has been set to partially cover the costs of website maintenance.

2. Gmail users are encouraged to check the Spam mailbox for registration/forgot password instructions. Sometimes the email containing these instructions is sent to Spam folder instead of regular Inbox.

3.For any query, registration or login assistance, please send an email to support@unitoperation.com.



Unit Operation is seeking applications from qualified chemical engineering professionals for content development on several core areas of chemical engineering. They are expected to work on time-bound, discrete assignments for fixed remunerations. The selected professional must be an M. Tech/ME, preferably a Ph. D, from a recognized institute/university, with excellent academic credentials and relevant teaching/industrial experience. Please send an email with your brief CV and your expertise/core area for content development to support@unitoperation.com .







 Terms and Conditions                  




Terms and Conditions


The website (www.unitoperation.com) is owned and operated by Unit Operation, registered office at 40/168 Bandipur Upanibesh Road, Ward No 4, Khardah, Kolkata, West Bengal 700118, India. Please read the Terms and Conditions carefully, as they constitute a binding contract between both the parties (Unit Operation : the executors, management, employees, directors, officers, agents, successors and assigns of Unit Operation and User: registrants, users and contributors to the website) and accept the same on understanding them thoroughly.

By the act of registration, subscription, usage and entering into this website, usage of any of the content and services therein, you agree that you have read, understood and are bound by the Terms stated herein. In the event the Terms stated herein are in disagreement or conflict with any other document / policy / content on our website, the Terms will prevail over them.


The Terms & Conditions set out in this website may be altered / amended based on policies adopted by Unit Operation at different intervals. If you do not agree with the Terms and Conditions and the Privacy Policy given in our website in their entirety, you are advised not to use www.unitoperation.com in any way and should exit from the website immediately.

Eligibility To Use

The website is available for registration and use only to persons who are eligible for entry and execution of legally binding contracts as stated herein. A minor may register and use the website, through legal guardian or parents. Unit Operation will not be responsible for any consequence arising out of abuse/misuse/misrepresentations of any kind of the website. We reserve the right to terminate registration and / or refuse access to the website for minors under the age of 18 years.

Account and Registration Obligations

The user of the website must be of legal age to form a binding contract and legally eligible for registration and use of website under the applicable laws of India. The user must provide true, accurate, current and complete information during registration or any other means of communication. For any reasonable grounds to suspect that information provided by a registrant/user is untrue, inaccurate, not current or incomplete, Unit Operation reserves the right to suspend or terminate the account and refuse any and all current or future access and/or use of the website (or any portion thereof). The registrant/user undertakes to indemnify Unit Operation for any loss, claim, damage, costs (including legal and professional costs) relating to any abuse or violation of the website.

Transfer of Account

The registrant/subscriber/user is prohibited from selling, trading, or transferring account details including username and password or any other information, in part or entirety, to another person/party. Unit Operation does not own responsibility in any manner over any dispute arising out of transmittal of any information-technical, non-technical or financial transactions by any third party using account/e-mail provided by the registrant/ subscriber/ user.

International Access

Unit Operation does not claim or represent directly or indirectly that any information/product/or services referred to in the materials/contents given on this website is appropriate or deemed to be appropriate for use outside India. Those who choose to access this website from outside India are responsible for compliance with local laws of the international registrant/user/subscriber, if and to the extent local laws are applicable.

Terms for Posting Content

If you are an individual/user who provides materials /contents/lessons/information for free or at a Cost, then you shall be termed as a Contributor. The Contributor agrees to abide and covenant the following additional terms and conditions:
a. All content submitted by the Contributor shall be subject to approval by Unit Operation, which may be granted or denied at its sole discretion.
b. If the Contributor chooses to charge fees for his Content/Contribution then he/she shall have to agree and to be a signatory to specific contract agreed mutually by both the parties.
c. The Contributor shall be responsible for all submitted Contents, that he owns or have the necessary licenses, rights, consents, and permissions, and have the authority to authorize Unit Operation, to reproduce, distribute, publicly perform (including by means of a digital/audio transmission), publicly display, communicate to the public, promote, market and that no submitted content shall infringe or misappropriate any intellectual property right of a third party. The Contributor shall be entirely responsible for accuracy and effectiveness of the contents submitted by him/her.
d. The Contributor hereby grants the Company (Unit Operation) a non-exclusive right and license to reproduce, distribute, publicly perform, offer, market and otherwise use and exploit the submitted Content on the website. Notwithstanding the foregoing, Unit Operation reserves the right to remove all or any portion of the submitted content from the website at any time.
e. The Contributor must have the required qualifications, credentials and expertise, including without limitation, education, training, knowledge, and skill sets, to contribute or teach or offer the services.
f. The Contributor shall not interfere with or otherwise prevent Unit Operation from providing or uploading the contributed content;
g. The Contributor shall not engage in any activity that will require Unit Operation to obtain any licenses from or pay any royalties to any third party for the submitted content/ information or products.
h. The Contributor must be over the age of 18.
i. To the extent permitted by applicable law, Unit Operation disclaims all warranties, expressed or implied, as to the accuracy of information contained in any of the materials on this website. Unit Operation shall not be liable to any person/organization for any loss or damage which may/potentially may arise from the use of any of the information/content contained in this website.

Terms for Accessing Content of the website

The Registrant/User in search/use of content provided in the website, the following additional terms and conditions apply, and represent, warrant and covenant that:
a. You have read, understood, and agree to be bound by the pricing information posted in the website (www.unitoperation.com) registration, payment of registration fee or usage of the website.
b. You are over the age of 18, or, if not, you will use the website only with the involvement, supervision, and approval or a parent or legal guardian.
c. You will not reproduce, distribute, publicly display, publicly perform, communicate to the public, create derivative works from or otherwise use and exploit any website content, except as permitted by these Terms and Conditions posted in the website.
d. When placing an order you undertake that all details you provide to us are true and accurate, that you are an authorized user of the credit or debit card used to place your order and that there are sufficient funds to cover the registration fee.
e. The registration fee for use of the website are subject to changes/revision from time to time as deemed appropriate and decided by the management without any prior notice.

Credit Card/Debit Card Details

You agree, understand and confirm that the financial details provided by you for availing of services on our website will be correct and accurate and you shall not use the credit card/debit card or any other financial instrument which is not lawfully owned by you. You further agree and undertake to provide the correct and valid financial details when making payment on our website. We shall not be liable in any event, for any financial fraud that occurs to you. The liability for use of a card fraudulently will be on you and the onus to prove otherwise shall be exclusively on you. For further details on credit card/net banking transaction, please review and understand the Terms and Conditions and Privacy Policy of payment gateway of the website (Avenues India Pvt. Ltd, https://www.ccavenue.com/; https://www.ccavenue.com/privacy.jsp) before proceeding for any payment, net banking and registration. If you do not agree with the Terms and Conditions and the Privacy Policy given in CCAvenue website in their entirety, you are advised not to proceed any further and should exit from the website immediately


In the event you are not satisfied with the information, contents, lessons, course materials contained in the website, you can seek refund of the amount paid by you for registration, after deduction of processing/transaction fees charged by the payment gateway and the banks- the total deduction not to exceed 10% of the registration fee- within 72 hours from the date and time of registration. Refunds are made to the same account from where the amount has been received by us. All refunds are processed within 20 days of receiving the request.

Electronic Communications

When you visit our website or send email(s) to us, you are communicating with us electronically. You agree to give your consent to receive communications from us electronically. You agree that all agreements, notices, disclosures and other communications that we provide to you electronically satisfy all legal requirements.

Abuse or Misuse of the website

The user hereby agrees that the user shall neither himself nor be part of any kind of abuse or misuse of the website in any manner whatsoever. The user shall not share, display, convey, transmit or portray any activity that abuses or misuses the website content in any manner whatsoever. Likewise, in the event the user feels that there is any kind of abusive content or such other information shared / displayed by the other party, the user shall immediately report the same to Unit Operation (unitopteam@gmail.com). In the event we have reasons to believe that the registrant/user is sharing, displaying, conveying, transmitting or portraying abusive content of any kind or part of such communication/transmission, Unit Operation reserves the absolute right to terminate the account and the services availed by the user without providing any reason whatsoever, apart from other measures. Similarly, the user hereby also agrees that he/she shall not inter-alia share, display or transmit any copyrighted material which he/she is not permitted to do in the course of the facilities availed of the website.

You Agree and Confirm

1. That you shall use the services provided by us, for lawful purposes only and shall comply with all applicable laws and regulations while using the website and transacting on the website.
2. You shall provide authentic and true information in all instances where such information is requested of you. We reserve the right to confirm and validate the information and other details provided by you at any point of time. If upon confirmation your details are found to be false (wholly or partly), we have the right and the sole discretion to reject the registration and debar you from using the services of our website and / or other affiliated websites without prior intimation whatsoever.
3. That you shall access the services available on this website and transact at your sole risk and shall use your best and prudent judgment before entering into any transaction through this website.

You Agree and Confirm That You Shall Not Use Our Website for Any of The Following Purposes:

1. Disseminating any unlawful, harassing, libellous, abusive, threatening, harmful, vulgar, obscene, or otherwise objectionable material.
2. Transmitting material that encourages conduct that constitutes a criminal offence, results in civil liability or breach of any relevant laws, regulations or code of practice.
3. Gaining unauthorized access to other computer systems.
4. Using, displaying, mirroring or framing of the wesbite, or any individual element within the website or services, Unit Operation name, any Unit Operation trademark, logo or other proprietary information, or the layout and design of any page or form contained on a page, without expressed written consent and a lawful, legal contract from Unit Operation.
5. Interfering with any other persons use or enjoyment of the website.
6. Breaching any applicable laws, rules or regulations.
7. Interfering or disrupting networks or websites connected to the Site.
8. Making, transmitting or storing electronic copies of materials protected by copyright without the permission of the copyright owner.
9. Collecting or storing any personally identifiable information from the website or services from other users of the websites , books journals, periodicals or services without their expressed permission.
10. Impersonating or misrepresenting your affiliation with any person or entity.
11. Violating any applicable law or regulation.
12. Encouraging or enabling any other individual to do any of the foregoing.
13. Any other activity as prohibited under the Indian Laws amended from time to time.

Modification of Terms & Conditions Of Service

We reserve the right at any time to modify the Terms of our website without any prior notification to you. Should you wish to terminate your account due to a modification to the Terms or the Privacy Policy, you may do so by emailing us at unitopteam@gmail.com. However, if you continue to use the service you shall be deemed to have agreed to accept and abide by the modified Terms of this website.

Reviews, Feedback, Submissions

All reviews, comments, feedback, postcards, suggestions, ideas, and other submissions disclosed, submitted or offered on or by our website, submitted or offered in connection with your use of this website (collectively, the Comments) shall be and remain our property. Such disclosure, submission or offer of any Comments shall constitute an assignment to us of all worldwide rights, titles and interests in all copyrights and other intellectual properties in the Comments. Thus, we own exclusively all such rights, titles and interests and shall not be limited in any way in its use, commercial or otherwise, of any Comments. We will be entitled to use, reproduce, disclose, modify, adapt, create derivative works from, publish, display and distribute any Comments you submit for any purpose whatsoever, without restriction and without compensating you in any way. We are and shall be under no obligation (1) to maintain any Comments in confidence; (2) to pay you any compensation for any Comments or use of comments; or (3) to respond to any Comments. You agree that any Comments submitted by you to our website shall not violate this policy or any right of any third party, including copyright, trademark, privacy or other personal or proprietary right(s), and shall not cause injury to any person or entity. You further agree that no Comments submitted by you to our website will be or contain libellous or otherwise unlawful, threatening, abusive or obscene material, or contain software viruses, bugs, worms, political campaigning, commercial solicitation, chain letters, mass mailings or any form of spam. We reserve the right (but not the obligation) to monitor and edit or remove any Comments submitted to our website. You grant us the right to use the name that you submit in connection with any Comments. You undertake not to use a false email address, impersonate any person or entity, or otherwise mislead as to the origin of any Comments you submit. You are and shall remain solely responsible for the content of any Comments that you make and you agree to indemnify us and our affiliates for all claims resulting from any Comments you submit. We and our affiliates take no responsibility and assume no liability for any Comments submitted by you or any third party.


All software, technology, designs, materials, information, communications, text, graphics, links, electronic art, animations, illustrations, artwork, audio clips, video clips, photos, images, reviews, ideas, and other data or copyrightable materials or content, including the selection and arrangements thereof is Content. Where the Unit Operation provides Content to you in connection with the Products, including, without limitation, the Software and the Products and the Site, it is Unit Operation’s Content. Content remains the proprietary property of Unit Operation and is protected, without limitation, pursuant to Indian & and foreign copyright and other intellectual property laws.


You agree to defend, indemnify and hold us and our employees, directors, officers, agents and their successors and assigns, harmless from and against any and all claims, liabilities, damages, losses, costs and expenses, including attorneys fees, caused by or arising out of or relating to claims based upon your actions or inactions, which may result in any loss or liability to us or any third party, including but not limited to breach of any warranties, representations or undertakings or in relation to the non-fulfilment of any of your obligations under these Terms of Use or arising out of the your violation of any applicable laws, regulations including but not limited to Intellectual Property Rights, payment of statutory dues and taxes, claim of libel, defamation, violation of rights of privacy or publicity, loss of service by other subscribers and infringement of intellectual property or other rights. This clause shall survive the expiry or termination of these Terms of Use.

Termination and Survival Of The Terms After The Term Ends

Unit Operation may terminate these Terms at any time. Without limiting the foregoing, Unit Operation shall have the right to immediately terminate your password or account or block your IP address, in the event of any conduct by you, which Unit Operation, in its sole discretion, considers to be unacceptable, or in breach of these Terms. You may terminate these Terms at any time, provided that you provide legal notice to Unit Operation and discontinue any further use of our website.

Limitation of Liability and Disclaimers

The website is provided without any warranties or guarantees and in an As Is condition. You must bear the risks associated with the use of the website. We will not be responsible for any errors or omissions or for the results obtained from the use of such information or for any technical problems you may experience with the website. This disclaimer constitutes an essential part of these Terms. To the fullest extent permitted under applicable law, we or our partners shall not be liable for any indirect, incidental, special, consequential or exemplary damages, including but not limited to, damages for loss of profits, goodwill, use, data or other intangible losses arising out of or in connection with the website, its services or these Terms. Without prejudice to the generality of the section above, our total liability to you for all liabilities arising out of these Terms. We, make no representations or warranties about the accuracy, reliability, completeness, relevance and/or timeliness of any content, information, software, text, graphics, links or communications provided on or through the use of the website or that the operation of the website will be error free and/or uninterrupted. Consequently, Unit Operation assumes no liability whatsoever for any monetary or other damage suffered by you on account of the delay, failure, interruption, or corruption of any data or other information transmitted in connection with use of the website; and/or any interruption or errors in the operation of the website.

Website Security

You are prohibited from violating or attempting to violate the security of the website, including, without limitation, (a) accessing data not intended for you or logging onto a server or an account which you are not authorized to access; (b) attempting to probe, scan or test the vulnerability of a system or network or to breach security or authentication measures; (c) attempting to interfere with service to any other user, host or network, including, without limitation, via means of submitting a virus, bug or worm or other file or software to the Site, overloading, flooding, spamming, mail bombing or crashing; (d) sending unsolicited email, including promotions and/or advertising of products or services; or (e) forging any TCP/IP packet header or any part of the header information in any email or newsgroup posting. Violations of system or network security may result in civil or criminal liability. Unit Operation will investigate occurrences that may involve such violations and may involve, and cooperate with, law enforcement authorities in prosecuting users who are involved in such violations. You agree not to use any device, software or routine to interfere or attempt to interfere with the proper working of this Site or any activity being conducted on this Site. You agree, further, not to use or attempt to use any engine, software, tool, agent or other device or mechanism (including without limitation browsers, spiders, robots, avatars or intelligent agents) to navigate or search this Site Our website can be used on most of the internet browsers.

Entire Terms

If any part of these Terms is determined to be invalid or unenforceable pursuant to applicable law including, but not limited to, the warranty disclaimers and liability limitations set forth above, then the invalid or unenforceable provision will be deemed to be superseded by a valid, enforceable provision that most closely matches the intent of the original provision and the remainder of the Terms shall continue in effect. Unless otherwise specified herein, these Terms and the website policies constitute the entire agreement between you and Unit Operation with respect to our sites/services and it supersedes all prior or contemporaneous communications and proposals, whether electronic, oral or written, between you and us with respect to Unit Operation. Our failure to act with respect to a breach by you or others does not waive our right to act with respect to subsequent or similar breaches.

Last Updated
20th April, 2018


Privacy Policy

The founding policy of Unit Operation is to operate the website (www.unitoperation.com) with highest standard of ethics and morality. By the act of registration and usage of the website, you agree to the terms of our privacy policy which has been stated and explained in more details in later section of this document. Before submission of any information what-so-ever, proceeding for the act of registration, payment of registration fee and/or net banking through our payment gateway please review and understand the Privacy Policies of Unit Operation and Avenues India Pvt. Ltd, ( which is the payment gateway of the website https://www.ccavenue.com/; https://www.ccavenue.com/privacy.jsp) and If you do not agree with the Terms and Conditions and the Privacy Policy given in this document and that of Avenues India Pvt. Ltd in their entirety, you are advised not to proceed any further for registration, payment of registration fee or usage of the website in any form, and should exit from the website immediately

Information on contact details (telephone, email, mobile number, shipping address, credit/debit card/net banking details etc), are collected during registration and/or payment of registration fee which you agree that this action constitutes a consent to our business relationship established using the information you provide to us. Please read the privacy policy given here in detail and that of CCAvenue (https://www.ccavenue.com/; https://www.ccavenue.com/privacy.jspduring ) regarding the collection, use, and disclosure of or your information. If you do not agree with any of the terms or policies described in this Privacy Policy, you are encouraged to immediately exit the website.

1. Privacy

Your privacy is very important to us. We follow systematic and stringent procedures to protect the security of the information / data stored on our website. The information that you have shared on our website is stored in secure server with encryption and can be accessed only for official purposes. Any of our employees, sub-contracted firms or agents who are in any form whatsoever related to operation , modification, upgrade or maintenance of the website, violate our privacy and/or security policies related to customer's data is subject to disciplinary action, including possible termination and civil and/or criminal prosecution.

2. Registration

On signing up on our website, you are required to provide us with certain basic mandatory information inter-alia including your e-mail id, name, mobile number, gender and a password. Once the registration is completed, the said e-mail id and password can be used to access your account every time you visit our website.

3. Information We Collect and That You Provide:

We collect information that is either anonymous or personally identifiable. When you visit our site to read or download information, we collect and store information, in order to improve security, analyse trends and administer the site. We use this information to evaluate traffic patterns on our site, so that we can make it more useful to our visitors. The information helps us to continually improve your experience at our website. We do not make this information available to third parties, nor do we use it for any other purpose, except as set out herein.

SMS and email: Upon subscribing to any services on our website, we shall be entitled to use your registered mobile number and email id on the website to send transaction related SMS and email to you.

Payment Information: We do not take Credit/Debit card or Net banking details on our website. On clicking the Submit and Pay Now option options, you will be redirected to a Secure Payment Gateway ( Avenues India Pvt. Ltd, https://www.ccavenue.com/; https://www.ccavenue.com/privacy.jsp) for completing the transaction. You will then be required to enter your relevant card details or other various net banking options and details on the page to complete the transaction. On successful completion of the transaction, you will be redirected to our website with your order details and order number being displayed. It is to be noted that we will not store any bank related information on our records and none of our staffs will hold or be exposed to this information.

4. Cookies

We do not use cookies for tracking purposes. Some of our pages contain Google Adsense advertisements which may use cookies for statistical analytics purposes. Google’s advertising requirements are securely protected by Google’s Advertising Principles https://support.google.com/ adwordspolicy/answer/1316548?hl=en. These Adsense cookies are files which identify your computer / your 'session' as a unique user when you visit pages on our website. Once you exit our site, these 'session cookies' expire (either when you close your browser or after 20 minutes). Google Adsense cookies use 'tracking cookies' to collect information regarding website usage (e.g., the number of visitors to different sections of our website) to analyze traffic to our website and improve user experience.. Google Adsense cookies are free from virus and do not contain any personal details. You may configure your browser to prevent cookies from being set on your computer.

5. Social Media Widgets

The website may include certain social media features, such as the 'Facebook /Tweeter' buttons. On using these features, the IP addresses of the user may be collected by these social networking sites depending on the page that is being visited and the Facebook or Tweeter websites may set cookies to enable the features and links to function properly. The interactions of the users with these features are governed by the privacy policy of the social networking companies, as the case may be.

6. Usage By Children

We do not knowingly collect, maintain or sell products or services to people under age 18 or use personal information from our website about children under age 18. Children should seek the consent of their parents before providing any information about themselves or their parents and other family members online.

Use and access to the website requires registration/Login details. While providing such information you accept that we may use personal information about you to improve the site, review the usage of the site, the content and design of the site.

7. Security

We have in place appropriate technical and security measures to prevent unauthorized or unlawful access to or accidental loss of or destruction or damage to your information. When we collect data through our website, we collect your personal details on a secured server. The payment details are entered on the Payment Gateway's or Bank's page on a secured SSL. The data is transferred between Bank and gateways in an encrypted manner.

Unit Operation utilizes various information security measures such as firewalls, encrypted data transmission and other security techniques to protect your personal data. However, please keep in mind that transmitting information via the internet is never completely secure and thus any information submitted may be intercepted, collected, used or disclosed by others. As per our security procedures we may occasionally request proof of identity before we disclose personal information to you. You are responsible for protecting against unauthorized access to your password and to your computer. We are not responsible for the security or confidentiality of communications you send to us through the internet using email messages.

8. Indemnify

'Your Information' is defined as any information you provide to us during registration, in the feedback area or through any email feature. We will protect Your Information in accordance with our Privacy Policy. If you use the Site, you are responsible for maintaining the confidentiality of Your Login ID and Password and for restricting access to your computer, and you agree to accept responsibility for all activities that occur under Your Login ID or Password. We shall not be liable to any person for any loss or damage which may arise as a result of any failure by you to protect your password or account. You undertake to indemnify and keep indemnified us for any loss, claim, damage, costs (including legal and professional costs) relating to your responsibility or liability or failure including those aforesaid. You agree to notify us immediately of any unauthorized use of your account or any other breach of security. We reserve the right to refuse service, terminate accounts, or remove or edit content in its sole discretion.

9. Safety and Security Tips

Protect your passwords.

10. Terms of Use, Notices, And Revisions

If you have any concern about privacy at our website, please contact us with a thorough description, and we will try to resolve it. Our business changes constantly, and our Privacy Policy and the Terms of Use will also change; but you should check our web site frequently to see recent changes. Unless stated otherwise, our current Privacy Policy applies to all information that we have about you and your account.

13. Reach Us

If you have any questions or comments regarding this privacy policy, please contact us via email at unitopteam@gmail.com or write to us at 40/168 Bandipur Upanibesh Road, Ward No 4, Khardah, Kolkata, West Bengal 700118.