Question

For a precious stone, 'carat' is used for specifying its mass. If 1 carat = 3.168 grains (a unit of mass) and 1 gram = 15.4 grains, find the total mass in kilogram of the ring that contains 0.5 carat diamond and 7 grant gold.

• A. $7.1\times {10}^{4}kg$
• B. $7.1\times {10}^{-4}kg$
• C. $7.1\times {10}^{3}kg$
• D. $7.1\times {10}^{-3}kg$

Answer 1

Answer: (D)

$7.1\times {10}^{-3}kg$

1 carat = 3.168 grains

1 gram = 15.4 grains

Thus,

0.500 carat diamond = $\frac{3.168}{15.4}$

0.500 carat diamond = 0.1 grams

Now total mass of ring in grams is, = 0.1 +7 =7.1gm

And in Kilograms ,

= $\frac{7.1\times 1kg}{1000g}$

= $7.1\times {10}^{-}3$kg