CLASS-XII COMPUTER SCIENCE SECOND TERM-END QUESTIONS & SOLUTIONS

1. A device that forwards data packet from one network to another is called Router
2. Which operator performs pattern matching? LIKE
3. Consider the following SQL statement. What type of statement is this?
   

   INSERT INTO teacher VALUES (10211, ‘Zela’, ‘Maths’,66000);

   DML

4. Which of the following devices can be used at the centre of a star topology? HUB
5. A repeater takes a weak and corrupted signal and regenerates it.
6. Which of the following is not a legal constraint for a CREATE TABLE command? DISTINCT
7. HTTP is the set of rules for transferring hypertext such as? ALL OF THEM
8. The domain for Government Organization and bodies is .gov
9. Select the odd one out? CDMA
10. In SQL, which command(s) is(are) used to change a table’s structure/characteristics? ALTER TABLE

1. To increase the size of a column in an existing table, use ALTER TABLE.
2. To define a column as a primary key primary key constraint is used in CREATE TABLE
3. Telnet is an internet utility that lets you log onto remote computer systems.
4. A worm is a program designed to replicate
5. To list the names of existing database, you can use SHOW DATABASES; command

1. Hacking is usually understood to be the unauthorized access of a computer. (TRUE)
2. Client-side scripting does not support interaction within a webpage. (FALSE)
3. HTML is not a word processing tool. (TRUE)
4. Two popular video conferencing protocols are H.323 and SIP. (TRUE)
5. DELETE FROM <table> command is same as DROP TABLE command. (FALSE)

1. Define 3G. 
   Ans: 3G (Third Generation) mobile communication technology is a broadband, packet-based transmission of text, digitized voice, video and multimedia at data rates up to 2 mbps, offering a consistent set of services to mobile computer and phone users no matter where they are located in the world.
2. What is VoIP?
   Ans: VOIP (Voice Over Internet Protocol) enables phone calls to be made using standard internet connection. VoIP technology enables traditional telephony services to operate over computer networks using packet-switched protocols.
3. What are Viruses?
   Ans: A computer virus is a small piece of software that can spread from one infected computer to another. The virus could corrupt, steal, or delete data on your computer-even erasing everything on your hard drive. A virus could also use other programs like your e-mail program to spread itself to other computers
4. Write two characteristics of Web 2.0.
   Ans: Web 2.0 is the second phase in the web’s evolution that architect web information for use and reuse. Web 2.0 facilitates two way communication. The Characteristics are:                  (i) Dynamic Web Interface: Web 2.0 has multiple channels of linking to the sources, users can connect each piece of content from any parts of information sources. E.g. Google Map.        (ii) Rich user experience: Web 2.0 user is not only having the provision to receive information but also they can review and comment on it. E.g. Amazon.com.
   (iii) Interoperability on the internet.
   (iv) Video sharing possible on the websites.
5. How do you enforce business rules on a database?
   Ans: To enforce business rules on a database use following constraint : –
   (i) Referential Integrity
   (ii) Unique Constraint
   (iii) Primary key Constraint
   (iv) A Foreign Key

CREATE TABLE IF NOT EXISTS Customer(
       cid int(7) primary key auto_increment,
       custName varchar(30),
       custAddr varchar(20),
       custCountry varchar(30),
       pinCode int(6),
       custPhone varchar(10)
      );
INSERT INTO Customer (custName, custAddr, custCountry, pinCode, custPhone) VALUES ('Lawmsangi', 'Ramthar', 'India', 796001, 9856584587);

(b)             “IBM SkillsBuild” is an educational NGO. It is setting up its new campus at Aizawl for its web-based activities. The campus has four buildings as show in diagram below
(i)

(ii) Training Building as it hosts the most computers
(iii) (1) Repeater: between Training & Accounts buildings as they have 110 m of distance.
(2) Hub/Switch: In Training building as it will be hosting server.

CREATE TABLE IF NOT EXISTS candidate(
cnum varchar(8),
cname varchar(3),
dob date
);

(ii) Which of the following can be a candidate key for candidate? Explain briefly.
Ans: cnum and scode can uniquely identify the other attributes of the table, and are candidate keys.
(iii) Identify the Primary key(s) and foreign key(s) of register.
Ans: cnum is the primary key and scode is the foreign key.
(b) Given the following tables:

Orders (ordNo, ordDate, prodNo, Qty)
Product (prodNo, descp, price)
Payment (ordNo, payment)

(i) Write an SQL command to create the Product table.
Ans:

CREATE TABLE IF NOT EXISTS Product(
prodNo int primary key auto_increment,
descp text,
price demical(6,2)
)ENGINE=InnoDB;

(ii) Write a query to delete all those records from table Orders whose complete payment has been made.
Ans:

DELETE FROM Orders WHERE ordNo = (SELECT ordNo FROM Payment WHERE payment IS NOT NULL);

1. Low cost: Electronic mail is an extremely cost-effective way to move information around, especially when it must be moved quickly. A three page letter to U.S.A can cost ₹ 200 through courier, or about ₹ 100 to fax. The same letter can be sent by e-mail for the cost of one local call.
2. Speed: Electronic mail can be delivered almost as fast as the wire can carry it.
3. Waste Reduction: E-mail goes a long way toward reducing the clutter of paper in the modern office, not to mention saving many trees.
4. Ease of use: It is easy to send an e-mail. You don’t have to retype it three times, find an envelope, go to the corner to buy stamp, and then find a mail box.
5. Record Maintenance: Because all messages are files, you can automatically maintain a record of communications with someone else.
6. Patience: E-mail waits until you read it. It doesn’t have the jangling urgency of a phone call.