The correct match is:

	List-I		List-II
a.	Micro	i.	${10}^{-15}$ m
b.	Mega	ii.	${10}^{-6}$ m
c.	Giga	iii.	${10}^6$ m
d.	Femto	iv.	${10}^9$ m

Codes:

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

The numbers 234,000 and 6.0012 can be represented in scientific notation as:
 

What is the difference between 0.50 mol Na₂CO₃ and 0.50 M Na₂CO₃?

Round up the following numbers into three significant figures: 
(i) 10.4107 
(ii) 0.04597

The following data was obtained when dinitrogen and dioxygen react together to form different compounds:

The law of chemical combination applicable to the above experimental data is:
1. Law of reciprocal proportions
2. Law of multiple proportions
3. Law of constant composition
4. None of the above.

An organic compound contains 80 % (by wt.) carbon and the remaining percentage of hydrogen. The empirical formula of this compound is:
[Atomic wt. of C is 12, H is 1] 
1. CH₃
2. CH₄
3. CH
4. CH₂

The molecular formula of a commercial resin used for exchanging ions in water softening is ${\mathrm{C}}_8{\mathrm{H}}_7{\mathrm{SO}}_3\mathrm{Na}<mspace\; width="1em"></mspace>\left(\mathrm{Mol}.<mspace\; width="1em"></mspace>\mathrm{Wt}.<mspace\; width="1em"></mspace>206\right)$. The maximum uptake of ${\mathrm{Ca}}^{2+}$ ions by the resin when expressed in mole per gram resin is:
\( \mathrm{C}_8 \mathrm{H}_7 \mathrm{SO}_3 \mathrm{Na}+\mathrm{Ca}^{2+} \rightarrow (\mathrm{C}_8 \mathrm{H}_7 \mathrm{SO}_{3}){_2} \mathrm{Ca}+ \mathrm{Na}^{+}\)

1. $\frac{1}{103}$

2. $\frac{1}{206}$

3. $\frac{2}{309}$

4. $\frac{1}{412}$

Find the dimensionless (unitless) terms among the following concentration expressions.