(a) Convert the following in kilogram.
(i) `0.91 xx 10^(-27)g` (mass of electron)
(ii) 1 fg (mass of human DNA molecule)
(b) Convert into metre.
(i) 1.4 Gm (diameter of Sun)
(ii) 40En (thickness of Milky way Galaxy)

Explanation

(a) (i) `0.91 xx 10^(-27)`g (mass of electron)
`1g = 10^(-3) kg`
or Unit factor, `1 = (10^(-3) kg)/(1 g)`
`therefore 0.91 xx 10^(-27) g = 0.91 xx 10^(-27) g xx (10^(-3) kg)/(1 g)`
`=9.1 xx 10^(-31)` kg
(ii) Mass of human DNA molecule = 1 fg
`1fg = 10^(-15)`g
or Unit factor, `1 =(10^(-15)g)/(1 fg)`
`1g = 10^(-3) kg`
or `=1 xx 10^(-18)` kg
(b) (i) 1.4 Gm (diameter of Sun)
We know 1 Gm `=10^(9)` m
or unit factor, `1=(10^(9) m)/(1 Gm)`
`therefore 1.4 Gm = 1.4 Gm xx (10^(9) m)/(1 Gm) = 1.4 xx 10^(9)` m
(ii) 40 Em (thickness of Milky way galaxy)
We know, `1 =(10^(18)m)/(1 Em)`
`therefore 40 Em = 40 Em xx (10^(18)m)/(1 Em) = 40 xx 10^(18)` m
or `=4.0 xx 10^(19)`m