Molecular Formula

Q.

Calculate the molar mass of benzene

Q. Calculate the volume occupied by (1)28u nitrogen gas (2)28g N2 gas at STP

Q.

Calculate the formula mass of Potassium sulphate $\left({\mathrm{K}}_2{\mathrm{SO}}_4\right)$.

Given: Atomic masses of K = 39u, S = 32u, 0 = 16u

Q. 1 mole of N₂ has number of nitrogen atoms.

1. 6.022 X 10²³
2. 3.011 X 10²³
3. 12.044 X 10²³

Q.

Write the formulae for Ethanol and calculate the molecular mass for Ethanol

Q.

What is an ion, anion and cation? Give example for each. [3 MARKS]

Q.

Correct the following statements:

(a) A molecular formula represents an element.

(b) Molecular formula of water ($H_{2}O$) represents 9 parts by mass of water.

(c) A balanced equation obeys the law of conservation of mass and so does an unbalanced equation.

(d) A molecule of an element is always monoatomic.

(e) CO and Co both represent cobalt.

Q.

What is the difference between molecular formula and structural formula?

Q. The chemical formula of ammonium nitrate is _________.

1. $N{H}_{4}N{O}_3$
2. $N{H}_4(N{O}_3{)}_2$
3. $(N{H}_4{)}_{2}N{O}_3$
4. $N{O}_{3}N{H}_4$

Q.

What is ${\text{Na}}_2{\text{CO}}_3$ made up of?

1. 1 molecule of Sodium Carbonate

2. 2 atoms of sodium

3. 1 atom of Carbon

4. 3 atoms of Oxygen

Q.

Which of the following is the correct formula of calcium bicarbonate?

1. $Ca(HC{O}_3{)}_2$

2. $CaHC{O}_3$

3. $CaC{O}_3$

4. $C{a}_{2}C{O}_3$

Q.

What is difference between valency and charge of an atom?

Q.

Write the formula of Bismuth nitrate.

Q. Question 4 (c)
Write the chemical formulae of the following:
(c) Copper nitrate

Q. How many helium atoms are present in 80 g of helium?

1. $12.044\times {10}^{24}$
2. $12.044\times {10}^{23}$
3. $12.044\times {10}^{21}$
4. $12.044\times {10}^{22}$

Q.

What is the empirical formula of ${\mathrm{C}}_2{\mathrm{H}}_2$ and ${\mathrm{C}}_6{\mathrm{H}}_6$?

Q. In the reaction 4A+2B+3C = A₄ B_{2​​​​​​​} C₃ ​​​​​​​what will be the number of moles of product formed, starting from 1 mole of A , 0.6 mole of B and 0.72 mole of C?

Q.

Which of the following is the correct order of boiling points?

1. HF > H₂O > NH₃> CH₄

2. H₂O > HF > NH₃> CH₄

3. HF > H₂O > CH₄> NH₃

4. H₂O > HF > CH₄> NH₃

Q.

A gaseous hydrocarbon contains 82.76% of Carbon. Given that Its vapor density Is 29. Find its molecular formula. [C = 12, H =1].

Q.

Mention the significances of molecular formulae.

Q.

Name the polyatomic ion that carries a positive charge.

Q.

A compound containing carbon, hydrogen, and oxygen. Combustion analysis of a $4.30\mathrm{g}$sample of butyric acid produced $8.59\mathrm{g}$ ${\mathrm{CO}}_2$ and$3.52\mathrm{g}{\mathrm{H}}_2\mathrm{O}$. Find the empirical formula.

Q.

The Formula unit mass of magnesium chloride is __________

Q.

Write the formulae for Caustic soda and calculate the molecular mass for Caustic soda

Q.

The smallest unit of a pure substance which always exist independently and can retain all the physical and chemical properties of that substance is called a molecule.

1. True
2. False

Q.

__________ is always capable of independent existence. (Atom/Molecule)

Q. Define molecular formula?

Q. Identify the correct molecular formula of sulphuric acid.

1. ${\text{CH}}_4$
2. ${\text{H}}_2{\text{SO}}_4$
3. $\text{NaCl}$
4. $\text{HCl}$

Q. Question 32
Complete the table on the basis of information available in the symbols given below.

(a) ${}_{17}^{35}Cl\left(b\right){}_6^{12}C\left(c\right){}_{35}^{81}Br$

Q. Chemical formula of lead sulphate and lead nitrate is __________ respectively.

1. $P{b}_2(S{O}_4{)}_3$, $Pb(N{O}_3{)}_2$
2. $P{b}_2\left(S{O}_4\right)$, $P{b}_2\left(NO\right)$
3. $Pb(SO{)}_4$, $Pb(NO{)}_2$
4. $Pb(SO{)}_4$, $Pb(N{O}_3{)}_2$