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ZnO is amphoteric in nature since it reacts with both alkali and acid producing salt and water.

i) ZnO + 2NaOH = Na2ZnO2 (Sodium zincate) + H2O ...   (where NaOH is an alkali)

ii) ZnO + 2HCl = ZnCl2 (Zinc chloride) + H2O  ...   (where HCl is an acid)

The fractional distillation is adopted for the mixture where the constituents have difference in boiling points less than 25 deg C.

EXTERNAL

Basic differences between the 3rd, 4th and 5th generation computers are : 1. 3rd generation computers were called mini computers as they were small in size but 4th generation computers were called micro computers as they were very small in size. 2. In 3rd generation, Integrated circuit (I.C.) and large scale integration (LSI) was used but in 4th generation computers were using microprocessor and very large scale integration (VLSI). 3. Main memory of 3rd generation was increased in form of PROM and DRAM whereas in 4th generation as EPROM and SRAM. 4. 5th generation computers are based on Artificial intelligence (AI) technique. 5. 5th generation computers can understand and respond to spoken words or surroundings using different sensors which is the major difference between any other generation to 5th generation computers.

Internet Service Provider (ISP):

 An internet service provider (ISP) is a company that provides web access to both businesses  and consumers.

• ISPs may also provide other services such as email services, domain registration, web hosting, and browser services.
• An ISP is considered to be an information service provider, storage service provider, internet network service provider (INSP), or a mix of all of them.
• Internet use has evolved from only those with university or government accounts having access to nearly everyone having access, whether it's paid or free.
• Access has gone from dial-up connections to high-speed broadband technology.

As noted above, internet service providers primarily provide their customers access to the internet—plain access providers that just handle the traffic between the individual and the internet as a whole. But there may also be other services bundled in depending on the customer's location and availability. Some of these services include:

• Email services
• Web hosting services
• Domain registration
• Browser and software packages 

  WORLD WIDE WEB: The World Wide Web (abbreviated as the Web or WWW) is a system of Internet servers that supports hypertext to access several Internet protocols on a single interface. Almost every protocol type available on the Internet is accessible on the Web. This includes e-mail, FTP, Telnet, and Usenet News. In addition to these, the World Wide Web has its own protocol that is   Hyper Text Transfer Protocol, or HTTP.

  The operation of the Web relies primarily on hypertext as its means of information retrieval. Hyper Text is a document containing words that connect to other documents. These words are called   links and are selectable by the user. A single hypertext document can contain links to many documents. In the context of the Web, words or graphics may serve as links to other documents, images, video, and sound. Links may or may not follow a logical path, as each connection is programmed by the creator of the source document. Overall, the Web contains a complex virtual web of connections among a vast number of documents, graphics, videos, and sounds.

  Producing hypertext for the Web is accomplished by creating documents with a language called Hyper Text Markup Language, or HTML. With HTML, tags are placed within the text to accomplish document formatting, visual features such as font size, italics and bold, and the creation of hypertext links. Graphics and multimedia may also be incorporated into an HTML document. HTML is an evolving language, with new tags being added as each upgrade of the language is developed and released. The World Wide Web Consortium (W3C), led by Web founder Tim Berners-Lee, coordinates the efforts of standardizing HTML. The W3C now calls the language XHTML and considers it to be an application of the XML language standard.

  E-MAIL: Electronic mail, or e-mail, allows computer users locally and worldwide to exchange messages. Each user of e-mail has a mailbox address to which messages are sent. Messages sent through e-mail can arrive within a matter of seconds.

  A powerful aspect of e-mail is the option to send electronic files to a person’s e-mail address. Non-ASCII files, known as binary files, may be attached to e-mail messages. These files are referred to as MIME attachments.

  MIME stands for Multimedia Internet Mail Extension, and was developed to help e-mail software handle a variety of file types. For example, a document created in Microsoft Word can be attached to an e-mail message and retrieved by the recipient with the appropriate e-mail program. Many e-mail programs, including Eudora, Netscape Messenger, and Microsoft Outlook, offer the ability to read files written in HTML, which is itself a MIME type.

Number system is a method of writing sequence of numbers gives a value. Decimal number system as we use in daily life., Binary number system is the method which computer understands or we say, digital circuits can understand. So binary numbers are 0 and 1. The combination of these leads to the next numbers. (2) in decimal is 10 in binary

MS Excel is a commonly used Microsoft Office application. It is a spreadsheet program which is used to save and analyse numerical data.

Fields and records are two basic components of a database, which is an organized collection of information, or data. The term "fields" refers to columns, or vertical categories of data; the term "records" refers to rows, or horizontal groupings of unique field data. Examples of both database components are seen in older, printed databases and also in modern, computer-based databases.

Effective communication leads to understanding. The communication process is made up of four key components. Those components include encoding, the medium of transmission, decoding, and feedback. There are also two other factors in the process, and those two factors are present in the form of the sender and the receiver.

Elements for communication:

1. APPROACH: timing of communication; choice of medium; tone and point of view (perspective, attitude, and relationship regarding the audience, purpose, and material); recognition of audience (reader vs. writer orientation); direct vs. indirect presentation (ordering of evidence and conclusions); persuasive strategies and rhetorical appeals (logos, pathos, ethos).

2. DEVELOPMENT: Organization (logical arrangement and sequence); evidence and support (relevance, specificity, accuracy, and sufficiency of detail); knowledge of subject and material; quality of perception, analysis, and insight.

3. CLARITY: Presentation of a thesis or central argument (statement of purpose, delineation or narrowing of a topic, the relevance of subordinate or secondary arguments); word choice; technical language and jargon; structure (sentence, paragraph, document); coherence devices (organizational statement, repetition of words and phrases, the progression from familiar to unfamiliar, topic and transitional sentences); textual markers (headings, highlighting, formatting features).

4. STYLE: Word choice (economy, precision, and specificity of language and detail; abstract vs. concrete language; action verbs vs. linking or weak verbs with nominalizations; figures of speech: schemes and tropes); tone (personality and humor); active vs. passive voice; sentence variety.

5. CORRECTNESS: Rules and conventions of spelling, grammar, punctuation, usage, and idiom; style (appropriateness of word choice and level of formality to audience, purpose, and material); social and cultural appropriateness; accuracy in proofreading.

A perfect Machine is a machine that achieves 100 percent efficiency. The entire input energy is expected to get converted into output energy. H/E due to friction and other imperfect components, the input energy is not entirely converted into output energy, which is why no machine could be termed as 'perfect machine'.