Order of Magnitude

Q. Using the concept of significant figures, match Column I with the correct number of significant figures in Column II.
$\begin{array}{cccc}& \text{Column I}& & \text{Column II}\\ i& 0.1234& \text{a.}& 5\\ ii& 1.2100\text{cm}& \text{b.}& 4\\ iii& 47.23÷2.3& \text{c.}& 1\\ iv& 3\times {10}^8& \text{d.}& 2\end{array}$

1. $i–b;ii–a;iii–d;iv–c$
2. $i–b;ii–a;iii–c;iv–d$
3. $i–b;ii–d;iii–a;iv–c$
4. $i–c;ii–a;iii–d;iv–b$

Q.

How many grains of rice should the king give to satisfy the champion ?

1. 100000

2. 1 million

3. 1 billion

4. none of these