# KVPY (Kishore Vaigyanik Protsahan Yojana) Stream SB-SX (Class 12 & 1st Year B.Sc.) Physics: Questions 66 - 68 of 268

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## Question number: 66

Appeared in Year: 2011

MCQ▾

### Question

Jet aircrafts fly at altitudes above 30, 000 ft where the air is very cold at – 400C and the pressure is 0.28 atm. The cabin is maintained at 1 atm pressure by means of a compressor which exchanges air from outside adiabatically. In order to have a comfortable cabin temperature of 250C, we will require in addition

### Choices

Choice (4) Response

a.

A heater to warm the air injected into the cabin

b.

An air-conditioner to cool the air injected into the cabin

c.

Neither a heater nor an air-conditioner; the compressor is sufficient

d.

Alternatively heating and cooling in the two halves of the compressor cycle

## Question number: 67

Appeared in Year: 2011

MCQ▾

### Question

Due to transitions among its first three energy levels, hydro genic atom emits radiation at three discrete wavelengths λ1, λ2, and λ3. Then

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 68

Appeared in Year: 2012

MCQ▾

### Question

A ball of mass m suspended from a rigid support by an inextensible massless string is released from a height h above its lowest point. At its lowest point it collides elastically with a block of mass 2m at rest on a frictionless surface. Neglect the dimensions of the ball and the block. After the collision the ball rises to a maximum height of –

### Choices

Choice (4) Response

a.

b.

c.

d.

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