Atoms and Molecules

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. Arrange the following in decreasing order of their boiling points.

$A$: n-butane

$B$: 2-methylbutane

$C$: n-pentane

$D$: 2, 2-dimethylpropane

1. $d>c>b>a$
   
   
2. $a>b>c>d$
   
   
3. $b>c>d>a$
   
   
4. $c>b>d>a$

Q. Specific heat of a metal is 0.1 cal/g and its equivalent weight is 31.8 its exact atomic weight is

Q.

The largest number of molecules are in?

1. $28\mathrm{g}\mathrm{CO}$

2. $54\mathrm{g}{\mathrm{N}}_2{\mathrm{O}}_5$

3. $36\mathrm{g}{\mathrm{H}}_2\mathrm{O}$

4. $46\mathrm{g}{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$

Q. If we have a $CuS{O}_4.5H_{2}O$ sample and it contains a total of 1116 oxygen atoms, find the number of formula units of $CuS{O}_4.5H_{2}O$ present in the sample.

1. 124
2. $9N_A$
3. $0.124N_A$
4. 279

Q.

Mass of 1 atom of Hydrogen is _____

1. 1.66 $\times$ ${10}^{-24}$ g

2. 1.67 $\times$ ${10}^{-20}$ g

3. 6.022 $\times$ ${10}^{-23}$ g

4. 6.022 $\times$ ${10}^{-20}$ g

Q. A piece of Cu contains $6.022\times {10}^{24}$ atoms. How many mole of Cu atoms does it contain?

1. 10 mole
2. 5 mole
3. 2 mole
   
4. 1 mole
   

Q. $1.22\text{g}$ of a monobasic acid is dissolved in $100\text{g}$ of benzene. Boiling point of solution increases by ${0.13}^{\circ }\text{C}$ with respect to pure benzene. Find the molecular mass of acid in benzene solvent (in $\text{u}$). Report your answer after dividing it by $100$ and round it off to the nearest integer.

$(K_b\text{of benzene}=2.6{\text{K kg mol}}^{-1}$)

Q.

Calculate the weight of ${10}^{22}$ atoms of carbon.

[ $\mathrm{C}=12$, Avogadros No. $=6\times {10}^{23}$].

Q.

A solid element burns completely in oxygen to give gaseous oxide without any change in volume. if the vapour density of oxide is 32, the equivalent weight would be?

Q. Which is not Variable? A. Valency B. Molecular Weight C. Equivalent Mass D. All Above

Q.

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

1. 12.044

2. 6.022

3. 3.011

4. 9.033

Q.

Can you please explain the concept of equivalent weights of different substances?

Q.

In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the option out of the choices given below in each question.

Assertion (A) One atomic mass unit is defined as one-twelfth of the mass of one carbon - 12 atom.

Reason (R) Carbon - 12 isotope is the most abundant isotope of carbon and has been chosen as the standard.

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(c) A is false but R is true

(d) Both A and R are false

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.

Can I get the formulae related to mole concept?

Q. Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.

Q.

The number of $C{l}^{-}$ and $C{a}^{+2}$ ions in 222g. of $CaC{l}_2$ are

1. 4N, 2N

2. 2N, 4N

3. 1N, 2N

4. 2N, 1N

Q. why we dont cancel out molecular mass and valency if they have a common factor in equivalent mass ?

Q. How many moles are there in $28$ grams of $C{O}_2$ ?

Q.

The Specific Heat of Metal Is 0.16. Its Approximate atomic weight would be :

1. 16

2. 20

3. 40

4. 64

Q. Empirical formula of a compound is $C{H}_{2}O$. Its molecular mass is $60$. The molecular formula will be :

1. $C{H}_{2}O$
2. $C_3{H}_6{O}_3$
3. $C_2{H}_4{O}_2$
4. none of these

Q. The number of chloride ions that surrounds the central ${Na}^{+}$ ion in $NaCl$ crystal is__________.

1. $6$
2. $4$
3. $8$
4. $12$

Q.

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

1. 20

2. 23

3. 25

4. 30

Q. An element have atomic number 19 and mass number 39. The number of neutron in its nucleus is-

1. 20
2. 19
3. 58
4. 39

Q. In sodium chloride structure, each $N{a}^{+}$ ion is surrounded by six $C{l}^{-}$ ions as nearest neighbours and _______ $N{a}^{+}$ ions as next nearest neighbours. Fill in the blank.

1. $13$
2. $14$
3. $12$
4. $6$

Q. Which of the following has smallest number of molecules?

1. $0.1$ mole of $C{O}_2$ gas
2. $11.2$ litres of $C{O}_2$ gas
3. $22g$ of $C{O}_2$ gas
4. $22.4\times 103ml$ of $C{O}_2$ gas

Q. Which of the following are present in an atom with atomic number $82$ and mass number $208$?

1. $82$ protons and $82$ electrons
2. $82$ protons, $82$ electrons and $126$ neutrons
3. $82$ neutrons, $126$ protons and $126$ electrons
4. $82$ protons and $82$ neutrons

Q. What will be the symbolic representation of the following statement?
2 atoms of phosphorous and 7 atoms of oxygen

1. $P{O}_7$
2. $P_2{O}_7$
3. $P_2{O}_5$
4. $P{O}_4$

Q. The metal strontium forms ions with the symbol $S{r}^{2+}$. Write down the formula for each of the following:
i) Strontium oxide ii) Strontium chloride iii) Strontium nitrate iv) Strontium sulphate