CBSE Class 10 Computer Applications Cyber Ethics, Computer Viruses and HTML Assignment Set 04

Answer: A worm is a self-replicating program that spreads on its own across a network without needing a host file or user action. A Trojan horse pretends to be a useful program, does not replicate itself, and works only when the user runs it, after which it harms the system or opens a back door.

Teacher's Note:
1. Think of a worm as spreading by itself and a Trojan as relying on being tricked into installation.
2. Always mention replication when comparing the two.

Answer: In an online backup, data is copied over the internet to a remote server (cloud) and can be restored from anywhere. In an offline backup, data is copied to a local device such as an external hard disk, DVD or pen drive, which does not need the internet but can be lost or damaged along with the computer.

Teacher's Note:
1. The key contrast is remote storage versus local storage.
2. Give one example of each to score full marks.

Answer: A boot sector virus infects the boot record of a hard disk or floppy/pen drive. It loads into memory every time the computer starts, before the operating system, and can then spread to other disks used in the system.

Teacher's Note:
1. The word boot tells you that the virus is activated at start-up.
2. Mention that it hides in the boot record, not in an ordinary file.

Answer: 1. Education: e-learning, online classes and digital libraries make learning available to all.
2. Communication: email, video calls and social media connect people instantly across the world.
3. Business and governance: online banking, e-commerce and e-governance save time and make services transparent.
4. Negative effects: cyber crime, loss of privacy, screen addiction and job losses due to automation.

Teacher's Note:
1. Always give both positive and negative impacts.
2. Short examples from daily life make the answer convincing.

Answer: 1. Install a good antivirus program and keep it updated.
2. Scan all pen drives and downloads before opening them.
3. Do not open email attachments or click links from unknown senders.
4. Keep the operating system and software patched, and keep a firewall on.
5. Take regular backups of important data.

Teacher's Note:
1. Prevention is about habits as well as software.
2. Mention updating the antivirus, since old definitions miss new viruses.

Answer: A hacker is a person who gains access to a computer system or network, often by exploiting weaknesses. Some hackers (black hat) do this illegally to steal or damage data. Ethical hacking is authorised testing of a system by a security expert (white hat) to find and fix weaknesses before criminals can use them.

Teacher's Note:
1. The difference lies in permission and intention.
2. Use the terms black hat and white hat to show good understanding.

Answer: 1. The name must be unique within the page.
2. It should be short, meaningful and should not contain spaces.
3. It is case sensitive, so the same case must be used when linking to it, as in <A HREF="#top">.

Teacher's Note:
1. The name of an anchor is the target that a link refers to.
2. Remember that a mismatch in capital letters breaks the link.

Answer: Cellspacing is the space between two adjacent cells of a table. Cellpadding is the space between the content of a cell and the border of that cell. Example: <TABLE BORDER="1" CELLSPACING="5" CELLPADDING="10">.

Teacher's Note:
1. Spacing is outside the cell; padding is inside the cell.
2. Both values are given in pixels.

Answer: COLSPAN makes a cell stretch across the given number of columns, and ROWSPAN makes a cell stretch down across the given number of rows. Example: <TD COLSPAN="2"> merges two columns, <TD ROWSPAN="3"> merges three rows.

Teacher's Note:
1. These attributes merge cells, like Merge Cells in a word processor.
2. Both are used in the <TD> or <TH> tag.

Answer: Use the BGCOLOR attribute in the <TD> tag (or <TR> for a whole row):
<TABLE BORDER="1">
<TR><TD BGCOLOR="yellow">Maths</TD><TD BGCOLOR="#99ccff">Science</TD></TR>
</TABLE>

Teacher's Note:
1. BGCOLOR accepts a colour name or a hexadecimal code.
2. Put it in <TR> to colour a full row at once.

Answer: Nesting means placing one list inside an item of another list. Example:
<OL>
<LI>Fruits
<UL><LI>Apple</LI><LI>Mango</LI></UL>
</LI>
<LI>Vegetables</LI>
</OL>
Here an unordered list is nested inside the first item of an ordered list.

Teacher's Note:
1. The inner list must be placed before the closing </LI> of its parent item.
2. Close the inner list before the outer one.

Answer: Use the START attribute of the <OL> tag. For example, <OL START="5"> makes the first item numbered 5, and the next items 6, 7 and so on.

Teacher's Note:
1. START changes only the first number of the list.
2. The TYPE attribute changes the style of numbering.

Answer: Alternate text is the text given in the ALT attribute of the <IMG> tag, as in <IMG SRC="logo.jpg" ALT="School logo">. It is displayed when the image cannot load, and it is read out by screen readers for visually impaired users.

Teacher's Note:
1. ALT stands for alternate and is useful for accessibility.
2. It should describe the image in a few words.

Answer: 1. Google Chrome: a fast, free browser from Google with tabbed browsing, sync across devices and a large library of extensions.
2. Mozilla Firefox: a free, open-source browser that focuses on privacy and customisation through add-ons.
(Microsoft Edge, Safari and Opera are other examples.)

Teacher's Note:
1. A browser is software used to view web pages.
2. Mention one distinct feature of each browser.

Answer: Use the BGCOLOR attribute in the <BODY> tag: <BODY BGCOLOR="lightblue"> (or a hex value such as "#ffffcc"). All the content of the page is then shown on that colour.

Teacher's Note:
1. The attribute belongs to the opening BODY tag.
2. A colour can be a name or a six-digit hex code.

Answer: The <B> tag is a container tag that displays the enclosed text in bold and needs </B> to close it. The <BR> tag is an empty tag that simply breaks the line and has no closing tag.

Teacher's Note:
1. B formats text, BR moves the text to a new line.
2. Only B has a closing tag.

Answer: Hypertext is text that contains links to other text, so a reader can jump from one document to another. A hyperlink is the actual clickable element (text or image) that connects to another page or to a different place on the same page.

Teacher's Note:
1. Hypertext is the idea; the hyperlink is the clickable item.
2. A link can be made from an image as well as text.

Answer: LINK sets the colour of unvisited links, VLINK sets the colour of links already visited, and ALINK sets the colour of a link at the moment it is clicked (active). Example: <BODY LINK="blue" VLINK="purple" ALINK="red">.

Teacher's Note:
1. V stands for visited and A for active.
2. These attributes are written in the BODY tag.

Answer: Comments are notes for the programmer that the browser does not display. They are written between <!-- and -->, for example <!-- This is the heading section -->.

Teacher's Note:
1. Comments make code easier to understand and maintain.
2. They are visible only in the source code.

Answer: 1. It is a markup language, not a programming language.
2. It uses tags enclosed in angle brackets.
3. It is platform independent and runs in any browser.
4. It is not case sensitive and supports links, images, tables and forms.

Teacher's Note:
1. Focus on what HTML does: it describes the structure of a page.
2. Write four distinct points.

Answer: <UL> creates an unordered list whose items carry bullets (disc, circle or square). <OL> creates an ordered list whose items are numbered or lettered (1, A, a, I, i). Both use <LI> for each item.

Teacher's Note:
1. U stands for unordered, O for ordered.
2. The TYPE attribute changes the marker in both.

Answer: Use the VSPACE attribute of the <IMG> tag, for example <IMG SRC="pic.jpg" VSPACE="20">. This leaves 20 pixels above and below the image, while HSPACE does the same on the left and right.

Teacher's Note:
1. V stands for vertical and H for horizontal.
2. Values are in pixels.

Answer: 1. World Wide Web (WWW): a collection of linked web pages that can be viewed using a browser.
2. Email: sending and receiving electronic messages and attachments quickly.
(Others: chat, video conferencing, e-commerce, file transfer.)

Teacher's Note:
1. The internet is the network, and services run over it.
2. Give a one-line use for each service.

Answer: 1. IP address: a unique numeric address of a computer on the network, for example 192.168.1.1.
2. Domain name (URL): a human-friendly name that is mapped to the IP address by the Domain Name System (DNS), for example www.example.com.

Teacher's Note:
1. Computers use numbers but people prefer names, and DNS translates between them.
2. Give an example for each address type.

Answer: ARPANET was a network started in 1969 by the US Department of Defense's Advanced Research Projects Agency to connect research computers. It introduced packet switching and, later, the TCP/IP protocols, and it grew into the worldwide internet we use today.

Teacher's Note:
1. ARPANET is regarded as the ancestor of the internet.
2. Mention the year 1969 and packet switching.