# IGCSE Physics Paper-1: Specimen Questions with Answers 86 - 88 of 149

## Question 86

### Question

MCQ▾

Find the amount of sample left after 18 hours if the half-life is 8 hours and has 0.37 g of the substance.

Choice (4)

a.

0.12 g

b.

0.03 g

c.

1.76 g

d.

7.68 g

c.

### Explanation

Here from given data

Formula of half-life is given as,

## Question 87

### Question

MCQ▾

The diagram shows a speed-time graph for a body moving with constant acceleration. What is the shaded area under the graph?

Choice (4)

a.

speed

b.

distance

c.

time

d.

acceleration

b.

### Explanation

Here in above figure the graph of speed vs time is given.

Then area under the graph denoted speed ⨯ time.

As we know that speed means velocity

Then in this graph area under the graph is distance.

## Question 88

### Question

MCQ▾

What leads to refraction when light travels from air to glass?

### Choices

Choice (4)

a.

The amplitude of the light waves changes.

b.

The color of the light changes.

c.

The frequency of the light waves changes.

d.

The speed of the light changes.