## ML Aggarwal Class 8 Solutions for ICSE Maths Chapter 2 Exponents and Powers Ex 2.2

Question 1.

Express the following numbers in standard form:

(i) 0.0000000000085

(ii) 0.000000000000942

(iii) 6020000000000000

(iv) 0.00000000837

Solution:

Question 2.

Express the following numbers in the usual form:

(i) 3.02 × 10^{-6}

(ii) 1-007 × 10^{11}

(iii) 5.375 × 10^{14}

(iv) 7.579 × 10^{-14}

Solution:

Question 3.

Express the number appearing in the following statements in standard form:

(i) The mass of a proton is 0.000000000000000000000001673 gram.

(ii) The thickness of a piece of paper is 0.0016 cm.

(iii) The diameter of a wire on a computer chip is 0.000003 m.

(iv) A helium atom has a diameter of m

(v) Mass of a molecule of hydrogen gas is about 0.00000000000000000000334 tons.

(vi) The human body has 1 trillion cells which vary in shapes and sizes.

(vii) The distance from the Earth of the Sun is 149,600,000,000 m.

(viii) The speed of light is 300,000,000 m/sec.

(ix) Mass of the Earth is 5,970,000,000,000,000,000,000,000 kg.

(x) Express 3 years in seconds.

(xi) Express 7 hectares in cm^{2}.

(xii) A sugar factory has annual sales of 3 billion 720 million kilograms of sugar.

Solution:

Question 4.

Compare the following:

(i) Size of a plant cell to the thickness of a piece of paper.

(ii) Size of a plant cell to the diameter of a wire on a computer chip.

(iii) The thickness of a piece of paper to the diameter of a wire on a computer chip.

Given size of plant cell = 0.00001275 m

Thickness of a piece of paper = 0.0016 cm

Diameter of a wire on a computer chip = 0.000003 m

Solution:

Question 5.

The number of red blood cells per cubic millimetre of blood is approximately 5.5 million. If the average body contains 5 litres of blood, what is the total number of red cell in the body? (1 litre = 1,00,000 mm^{3})

Solution:

Question 6.

Mass of Mars is 6.42 × 10^{29} kg and the mass of the sun is 1.99 × 10^{30} kg. What is the total mass?

Solution:

Question 7.

A particular star is at a distance of about 8.1 × 10^{13} km from the Earth. Assuming that the light travels at 3 × 10^{8} m/sec, find how long does light take from that star to reach the Earth.

Solution:

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