# IGCSE Physics Paper-1: Specimen Questions with Answers 84 - 87 of 149

## Question number: 84

MCQ▾

### Question

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

### Choices

Choice (4) | |
---|---|

a. | 0.03 g |

b. | 7.68 g |

c. | 1.76 g |

d. | 0.12 g |

### Answer

c.### Explanation

Here from given data

Formula of half-life is given as,

## Question number: 85

MCQ▾

### Question

How we find density of a regularly-shaped block?

### Choices

Choice (4) | |
---|---|

a. | a measuring cylinder and a beaker |

b. | a measuring cylinder and a ruler |

c. | a balance and a ruler |

d. | a balance and a force meter (spring balance) |

### Answer

c.### Explanation

Here we want to measure density of regular shape so from formula,

Therefore from measuring mass a balance is used and Volume is measured by ruler.

Ruler is a straight strip with a smooth edge which is use as a guide in drawing straight line. Then we can measure perfect shape

So we should use a balance and a ruler.

## Question number: 86

MCQ▾

### Question

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

### Choices

Choice (4) | |
---|---|

a. | 0.12 g |

b. | 0.03 g |

c. | 1.76 g |

d. | 7.68 g |

### Answer

c.### Explanation

Here from given data

Formula of half-life is given as,

## Question number: 87

MCQ▾

### Question

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

### Choices

Choice (4) | |
---|---|

a. | speed |

b. | distance |

c. | time |

d. | acceleration |

### Answer

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.