A. 21
B. 18
C. 15
D. 12

Correct Answer: Option A

A. 21

Explanation

768→384→192→96→48→24→12→6

7 x 3 = 21yrs

SEE ALSO  Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 105 Jkg‾¹ specific heat capacity of water 4.2 x 10³ J kg‾¹ K‾¹]

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