# 3i Infotech Placement: Sample Questions 644 - 646 of 1245

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## Question 644

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### Describe in Detail

Essay▾

What is a scope resolution operator?

### Explanation

• The scope resolution operator “::” is used to qualify hidden names.
• We can use the unary scope operator if a namespace scope or global scope name is hidden by an explicit declaration of the same name in a block or class.

Example:

1. intcount=0;
2. intmain(void)
3. {
4.     intcount=0;
5.     :: count =1;
6.     count =2;
7.     return0;
8. }

## Question 645

### Question

MCQ▾

The mass number of a nucleus is

### Choices

Choice (4)

a.

Always less than its atomic number

b.

Sometimes more than and sometimes equal to its atomic number

c.

Always more than its atomic number

d.

All of the above

b.

### Explanation

• The mass number of a nucleus is sometime more than and sometimes equal to its atomic number.
• Mass number protons neutrons
• Atomic number is number of protons.
• So, mass number of a nucleus is sometimes more than and sometime equal its atomic number (in case of hydrogen) .

## Question 646

Edit

### Describe in Detail

Essay▾

What are the possible ways of data exchange?

### Explanation

Simplex:

• Travels in only one direction.
• Example- person talking into microphone and then hearing voice from the speaker.
• Keyboard connected to CPU provides simplex communication- CPU never needs to send characters to the keyboard but the keyboard always send characters to the CPU.

Half-duplex:

• Capable of sending signal in both directions- only one direction at a time.
• Example- police car radio phones allowing one person to talk at a time but both sides can talk to one-another.

Full-duplex:

• Data can be transmitted in both directions simultaneously.
• A local area network has full-duplex transmission, one workstation can be sending data on the line while another workstation is receiving data.
• Full-duplex transmission necessarily implies a bidirectional line.
• Example- telephone IP service.
• Also called bidirectional transmission.

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