Some Basic Concepts in Chemistry — JEE Main PYQs

The ratio of mass percentage (w/w) of C : H in a hydrocarbon is 12 : 1. It has two carbon atoms. The weight (in g) of $\mathrm{CO_2}$(g) formed when 3.38 g of this hydrocarbon is completely burnt in oxygen is :

(Given : Molar mass in g mol$^{-1}$ C : 12, H : 1, O : 16)

Number of moles and number of molecules in 1.4187 L of $\mathrm{SO_2}$ at STP respectively are

The correct order of total number of atoms present in

(A) 2 moles of cyclohexane

(B) 684 g of sucrose

(C) 90.8 L of dihydrogen at STP

is:

How many grams of residue is obtained by heating 2.76 g of silver carbonate?

(Given : Molar mass of C, O and Ag are 12, 16 and 108 $\mathrm{g\ mol^{-1}}$ respectively)

What volume of hydrogen gas at STP would be liberated by action of 50 mL of $\mathrm{H_2SO_4}$ of 50% purity (density $= 1.3\ \mathrm{g\ mL^{-1}}$) on 20 g of zinc?

Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65 $\mathrm{g\ mol^{-1}}$ respectively.

An oxide of iron contains 69.9% iron, its empirical formula, is:

(Given : Molar mass of Fe and O are 56 and 16 g mol$^{-1}$ respectively.)

Which of the following contain the same number of atoms?

(Given : Molar mass in g mol$^{-1}$ of H, He, O and S are 1, 4, 16 and 32 respectively)

A. 2 g of $\mathrm{O_2}$ gas

B. 4 g of $\mathrm{SO_2}$ gas

C. 1400 mL of $\mathrm{O_2}$ at STP

D. 0.05 L of He at STP

E. 0.0625 mol of $\mathrm{H_2}$ gas

Choose the correct answer from the options given below :

Match List - I with List - II.

	List - I (Mass of substance)		List - II (Number of atoms)
A.	1.8 mg water	I.	$2 \times 10^{-4} \times \mathrm{N_A}$
B.	9.8 mg sulphuric acid	II.	$1.5 \times 10^{-4} \times \mathrm{N_A}$
C.	1.8 mg carbon	III.	$3 \times 10^{-4} \times \mathrm{N_A}$
D.	5.85 mg salt (NaCl)	IV.	$7 \times 10^{-4} \times \mathrm{N_A}$

Choose the correct answer from the options given below :

$\mathrm{CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)}$

Consider the above reaction, what mass of $\mathrm{CaCl_2}$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $\mathrm{CaCO_3}$ ?

(Given : Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 $\mathrm{g\ mol^{-1}}$, respectively)

Among $10^{-9}$ g (each) of the following elements, which one will have the highest number of atoms?

Element: Pb, Po, Pr and Pt

Mass of magnesium required to produce 220 mL of hydrogen gas at STP on reaction with excess of dil. HCl is

Given: Molar mass of Mg is $24\ \mathrm{g\ mol^{-1}}$.

10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is :

The amount of calcium oxide produced on heating 150 kg limestone (75% pure) is _________ kg. (Nearest integer)

Given : Molar mass (in $\mathrm{g\ mol^{-1}}$) of Ca-40, O-16, C-12

At the sea level, the dry air mass percentage composition is given as nitrogen gas: 70.0, oxygen gas: 27.0 and argon gas: 3.0. If total pressure is 1.15 atm, then calculate the ratio of following respectively:

(i) partial pressure of nitrogen gas to partial pressure of oxygen gas

(ii) partial pressure of oxygen gas to partial pressure of argon gas

(Given: Molar mass of N, O and Ar are 14, 16 and 40 g mol$^{-1}$ respectively.)

Thyroxine, the hormone has given below structure

[Figure: thyroxine structure — HO-substituted benzene ring bearing two iodine atoms, linked via an ether oxygen to a second benzene ring bearing two iodine atoms, which carries a $\mathrm{CH_2CH(NH_2)COOH}$ side chain]

The percentage of iodine in thyroxine is ______%. (nearest integer)

(Given molar mass in g mol$^{-1}$ C:12, H:1, O:16, N:14, I:127)

Butane reacts with oxygen to produce carbon dioxide and water following the equation given below.

$$\mathrm{C_4H_{10}(g) + \frac{13}{2}O_2(g) \rightarrow 4CO_2(g) + 5H_2O(l)}$$

If 174.0 kg of butane is mixed with 320.0 kg of $\mathrm{O_2}$, the volume of water formed in liters is __________. (Nearest integer)

[Given : (a) Molar mass of C, H, O are 12, 1, 16 $\mathrm{g\ mol^{-1}}$ respectively, (b) Density of water = $1\ \mathrm{g\ mL^{-1}}$]

20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is __________ M. (Nearest Integer value)

(Given : Na = 23, I = 127, Ag = 108, N = 14, O = 16 g mol$^{-1}$)

Some $\mathrm{CO_2}$ gas was kept in a sealed container at a pressure of 1 atm and at 273 K. This entire amount of $\mathrm{CO_2}$ gas was later passed through an aqueous solution of $\mathrm{Ca(OH)_2}$. The excess unreacted $\mathrm{Ca(OH)_2}$ was later neutralized with 0.1 M of 40 mL HCl. If the volume of the sealed container of $\mathrm{CO_2}$ was x, then x is ________ $\mathrm{cm^3}$ (nearest integer).

[Given : The entire amount of $\mathrm{CO_2(g)}$ reacted with exactly half the initial amount of $\mathrm{Ca(OH)_2}$ present in the aqueous solution.]

20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is __________ $\times 10^{-2}$ M. (Nearest integer)

After removal of $10^{21}$ molecules from '$x$' mg sample of $\mathrm{CO_2}$, $2.8 \times 10^{-3}$ mol of it are left. The mass of $\mathrm{CO_2}$ taken initially is :

Given : $\mathrm{N_A} = 6.02 \times 10^{23}\ \mathrm{mol^{-1}}$

When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is ________. (Nearest integer)

Given :

Molar mass of Al is $27.0\ \mathrm{g\ mol^{-1}}$

Molar mass of O is $16.0\ \mathrm{g\ mol^{-1}}$

Consider the following reaction occurring in the blast furnace: $$\mathrm{Fe_3O_{4(s)} + 4CO_{(g)} \to 3Fe_{(l)} + 4CO_{2(g)}}$$ '$x$' kg of iron is produced when $2.32 \times 10^3$ kg $\mathrm{Fe_3O_4}$ and $2.8 \times 10^2$ kg CO are brought together in the furnace. The value of '$x$' is ______. (nearest integer) {Given: molar mass of $\mathrm{Fe_3O_4}$ = 232 g mol$^{-1}$ molar mass of CO = 28 g mol$^{-1}$ molar mass of Fe = 56 g mol$^{-1}$}

X g of benzoic acid on reaction with aq $\mathrm{NaHCO_3}$ released $\mathrm{CO_2}$ that occupied 11.2 L volume at STP. X is ______.

The elemental composition of a compound is 54.2% C, 9.2% H and 36.6% O. If the molar mass of the compound is $132\ \mathrm{g\ mol^{-1}}$, the molecular formula of the compound is :

[Given : The relative atomic mass of $\mathrm{C:H:O = 12:1:16}$]

[Stem unrecoverable: the PDF pages carrying this question's stem are corrupted in both the English and Hindi copies. The options indicate a five-statement (A-E) multiple-select question. Option texts below are recovered from the Hindi copy.]

The molarity of a 70% (mass/mass) aqueous solution of a monobasic acid (X) is _____ $\times\ 10^{-1}$ M(Nearest integer)

[Given: Density of aqueous solution of (X) is $1.25\ \mathrm{g\ mL^{-1}}$

Molar mass of the acid is $70\ \mathrm{g\ mol^{-1}}$ ]

Concentrated nitric acid is labelled as 75% by mass. The volume in mL of the solution which contains 30 g of nitric acid is __________.

Given : Density of nitric acid solution is $1.25\ \mathrm{g/mL}$.

The Molarity (M) of an aqueous solution containing 5.85 g of NaCl in 500 mL water is : (Given : Molar Mass Na : 23 and Cl : 35.5 gmol$^{-1}$)

Choose the Incorrect Statement about Dalton's Atomic Theory

The incorrect postulates of the Dalton's atomic theory are :

(A) Atoms of different elements differ in mass. (B) Matter consists of divisible atoms. (C) Compounds are formed when atoms of different element combine in a fixed ratio. (D) All the atoms of given element have different properties including mass. (E) Chemical reactions involve reorganisation of atoms.

Choose the correct answer from the options given below :

The number of moles of methane required to produce $11 \mathrm{~g} \mathrm{~CO_2(g)}$ after complete combustion is : (Given molar mass of methane in $\mathrm{g} \mathrm{~mol}^{-1}$ : 16)

Combustion of glucose $\mathrm{(C_6H_{12}O_6)}$ produces $\mathrm{CO_2}$ and water. The amount of oxygen (in g) required for the complete combustion of 900 g of glucose is :

[Molar mass of glucose in $\mathrm{g\ mol^{-1}}$ = 180]

A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ________ (Integer answer) (Given : Molar mass in $\mathrm{g\ mol^{-1}}$ Ethyl alcohol : 46 water : 18)

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 'A' $\times\ 10^{12}$ hertz and that has a radiant intensity in that direction of $\frac{1}{\text{'B'}}$ watt per steradian.

'A' and 'B' are respectively

Consider the following reaction :

$$\mathrm{3PbCl_2 + 2(NH_4)_3PO_4 \rightarrow Pb_3(PO_4)_2 + 6NH_4Cl}$$

If 72 mmol of $\mathrm{PbCl_2}$ is mixed with 50 mmol of $\mathrm{(NH_4)_3PO_4}$, then the amount of $\mathrm{Pb_3(PO_4)_2}$ formed is ________ mmol (nearest integer).

10 mL of gaseous hydrocarbon on combustion gives 40 mL of $\mathrm{CO_2(g)}$ and 50 mL of water vapour. Total number of carbon and hydrogen atoms in the hydrocarbon is ________.

Mass of methane required to produce 22 g of $\mathrm{CO_2}$ after complete combustion is ________ g.

(Given Molar mass in $\mathrm{g\ mol^{-1}}$   C = 12.0   H = 1.0   O = 16.0)

A solution of $\mathrm{H_2SO_4}$ is 31.4% $\mathrm{H_2SO_4}$ by mass and has a density of $1.25\,\mathrm{g/mL}$.

The molarity of the $\mathrm{H_2SO_4}$ solution is ________ M (nearest integer)

[Given molar mass of $\mathrm{H_2SO_4} = 98\,\mathrm{g\ mol^{-1}}$]

The mass of sodium acetate ($\mathrm{CH_3COONa}$) required to prepare 250 mL of 0.35 M aqueous solution is ________ g. (Molar mass of $\mathrm{CH_3COONa}$ is 82.02 $\mathrm{g\ mol^{-1}}$)

0.05 cm thick coating of silver is deposited on a plate of 0.05 $\mathrm{m^2}$ area. The number of silver atoms deposited on plate are ________ $\times 10^{23}$. (At mass Ag = 108, d = 7.9 $\mathrm{g\ cm^{-3}}$)

If a substance 'A' dissolves in solution of a mixture of 'B' and 'C' with their respective number of moles as $\mathrm{n_A}$, $\mathrm{n_B}$ and $\mathrm{n_C}$, Mole fraction of C in the solution is :

Number of moles of methane required to produce $22\,\mathrm{g}$ $\mathrm{CO_{2(g)}}$ after combustion is $x \times 10^{-2}$ moles. The value of $x$ is ________.

A sample of $\mathrm{CaCO_3}$ and $\mathrm{MgCO_3}$ weighed $2.21\ \mathrm{g}$ is ignited to constant weight of $1.152\ \mathrm{g}$. The composition of mixture is :

(Given molar mass in $\mathrm{g\ mol^{-1}}$ $\mathrm{CaCO_3}$ : 100, $\mathrm{MgCO_3}$ : 84)

The molarity of 1 L orthophosphoric acid ($\mathrm{H_3PO_4}$) having 70% purity by weight (specific gravity $1.54\ \mathrm{g\ cm^{-3}}$) is ________ M.

(Molar mass of $\mathrm{H_3PO_4}$ = $98\ \mathrm{g\ mol^{-1}}$)