1

### NEET 2013 (Karnataka)

In an unbiased p-n junction, holes diffuse from the p-region to n-region because of
A
The attraction of free electrons of n-region.
B
The higher hole concentration in p-region than that in n-region.
C
The higher concentration of electrons in the n-region than that in the p-region.
D
The potential difference across the p-n junction.

## Explanation

The higher hole concentration is in p-region than that in n-region.
2

### NEET 2013

The output (X) of the logic circuit shown ion figure will be

A
X = A . B
B
X = $\overline {A + B}$
C
X = $\overline {\overline A } .\overline {\overline B }$
D
X = $\overline {A.B}$

## Explanation

The output of the given logic circuit is

X = $\overline{\overline {A.B}}$ = A.B
3

### NEET 2013 (Karnataka)

The output from a NAND gate is divided into two in parallel and fed to another NAND gate. The resulting gate is a

A
AND gate
B
NOR gate
C
OR gate
D
NOT gate

## Explanation

C' = $\overline {A.B}$

$\Rightarrow$ C = $\overline{\overline {A.B}}$ = A.B

Hence the resultant gate is AND gate.
4

### NEET 2013

In a n-type semiconductor, which of the following statement is true.
A
Holes are minority carries and pentavalent atoms are dopants.
B
Holes are majority carries and trivalent atoms are dopants.
C
Electrons are majority carries and trivalent atoms are dopants.
D
Electrons are minority carriers and pentavalent atoms are dopants.

## Explanation

In n-type semiconductor, electrons are majority charge carriers and holes are minority charge carriers and pentavalent atoms are dopants.