Atoms and Molecules

Q.

What is the formula of unit Mass?

Q.

Calculate the formula mass of the following compound:

Aluminium oxide $\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$

Q. What is the relative atomic mass and atomic mass of calcium?

1. $40.0,40\text{u}$
2. $39.90,40.078\text{u}$
3. $40.078,40.078\text{u}$
4. $40.078,41.0\text{u}$

Q.

Calculate the formula mass of Sodium oxide $\left({\mathrm{Na}}_2\mathrm{O}\right)$.

Given: Atomic masses of Na = 23u, 0 = 16u

Q. What is the relative atomic mass and atomic mass of calcium?

1. $40.0,40\text{u}$
2. $39.90,40.078\text{u}$
3. $40.078,40.078\text{u}$
4. $40.078,41.0\text{u}$

Q.

The specific heat of a metal is 0.16 its approximate atomic weight would be

1. 32

2. 16

3. 40

4. 64

Q.

Calculate the formula mass of Potassium carbonate $\left({\mathrm{K}}_2{\mathrm{CO}}_3\right)$.

Given: Atomic masses of K = 39u, C = 12u, 0 = 16u

Q. If we consider that $\frac{1}{6}$, in place of $\frac{1}{12}$, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

1. Decrease twice
2. Remain unchanged
3. Increase two fold

4. Be a function of the molecular mass of the substance

Q. The atomic weight of two elements A and B are 40 and 80 respectively. If $xg$ of A contains y atoms, how many atoms are present in $2xg$ of B?

1. $\frac{y}{2}$

2. $2y$

3. $\frac{y}{4}$

4. $y$

Q.

Formula unit mass for $\mathrm{ZnO}$ is

Q. How many moles of Magnesium Phosphate $\left(M{g}_3\right(P{O}_4{)}_2)$ will contain $0.25$ mole of oxygen atoms?

1. $1.25\times {10}^{-2}$
2. $2.5\times {10}^{-2}$
3. $2\times {10}^{-2}$
4. $3.125\times {10}^{-2}$

Q.

Number of gram atoms of oxygen present in $0.3mole$ of $(COOH{)}_2.2H_{2}O$ is

1. 9

2. 18

3. 0.9

4. 1.8

Q.

1 mole of He gas has 6.022$\times$10x atoms. x is _____

1. 20

2. 23

3. 25

4. 30

Q. 1 mole of $N_2$ has _____ number of atoms.

1. 6.022 $\times$ ${10}^{23}$
2. 3.011 $\times$ ${10}^{23}$
3. 12.044 $\times$ ${10}^{23}$
4. 6.022 $\times$ ${10}^{22}$

Q.

How many oxygen atoms are present in 50g of $CaC{o}_3$ ?

1. 3.011 $\times$ ${10}^{23}$

2. 6.022 $\times$ ${10}^{23}$

3. 9.033 $\times$ ${10}^{23}$

4. 12.044 $\times$ ${10}^{23}$

Q.

Calculate the formula unit mass of ${\mathrm{CaCl}}_2$.