Some basic concepts OF Chemistry
189 Questions
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JEE (Main) Jan. 2025
Q1
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MCQ
The purification method based on the following physical transformation is
Solid $\xrightarrow[\text{(X)}]{\text{Heat}}$ Vapour $\xrightarrow[\text{(X)}]{\text{Cool}}$ Solid
A.
Sublimation
B.
Distillation
C.
Crystallization
D.
Extraction
JEE (Main) Jan. 2025
Q2
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MCQ
Choose the correct statements
(A) Weight of a substance is the amount of matter present in it
(B) Mass is the force exerted by gravity on an object
(C) Volume is the amount of space occupied by a substance
(D) Temperature below $0^{\circ}$ C are possible in Celsius scale, but in Kelvin scale negative temperature is not possible
(E) Precision refers to the closeness of various measurements for the same quantity
(A) Weight of a substance is the amount of matter present in it
(B) Mass is the force exerted by gravity on an object
(C) Volume is the amount of space occupied by a substance
(D) Temperature below $0^{\circ}$ C are possible in Celsius scale, but in Kelvin scale negative temperature is not possible
(E) Precision refers to the closeness of various measurements for the same quantity
A.
(B), (C) and (D) only
B.
(A), (B) and (C) only
C.
(A), (D) and (E) only
D.
(C), (D) and (E) only
JEE (Main) Jan. 2024
Q3
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The quantity which changes with temperature is
A.
Molarity
B.
Mass percentage
C.
Molality
D.
Mole fraction
JEE (Main) Jan. 2024
Q4
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A sample of $CaCO_{3}$ and $MgCO_{3}$ weighed 2.21g is ignited to constant weight of 1.152g. The composition of mixture is
(Given molar mass in $gmol^{-1}:CaCO_{3}:100,MgCO_{3}:84$ )
A.
$1.187gCaCO_{3}+1.023gMgCO_{3}$
B.
$1.023gCaCO_{3}+1.023gMgCO_{3}$
C.
$1.187gCaCO_{3}+1.187gMgCO_{3}$
D.
$1.023gCaCO_{3}+1.187gMgCO_{3}$
JEE (Main) April 2024
Q5
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The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 'A'Ć10 $^{12}$ hertz and that has a radiant intensity in that direction of $\frac{1}{B'}$ watt per steradian. 'A' and 'B' are respectively
A.
540 and $\frac{1}{683}$
B.
540 and 683
C.
450 and $\frac{1}{683}$
D.
450 and 683
JEE (Advanced) 2024
Q6
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At room temperature, disproportionation of an aqueous solution in situ generated nitrous acid ( $HNO_{2}$ ) gives the species
A.
$H_{3}O^{+}, NO_{3}^{-}$ and NO
B.
$H_{3}O^{+}, NO_{3}^{-}$ and $NO_{2}$
C.
$H_{3}O^{+}, NO^{-}$ and $NO_{2}$
D.
$H_{3}O^{+}, NO_{3}^{-}$ and $N_{2}O$
JEE (Main) Jan. 2023
Q7
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When a hydrocarbon A undergoes complete combustion it requires 11 equivalents of oxygen and produces 4 equivalents of water. What is the molecular formula of A
A.
$C_{9}H_{8}$
B.
$C_{11}H_{4}$
C.
$C_5H_{8}$
D.
$C_{11}H_{8}$
JEE (Main) April 2023
Q8
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$2IO_{3}^{-} + xI^{-} + 12H^{+} \rightarrow 6I_{2} + 6H_{2}O$ What is the value of $x$
A.
12
B.
2
C.
6
D.
10
JEE (Main) April 2023
Q9
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MCQ
Which of the following have same number of significant figures
(a) 0.00253 (b) 1.0003
(C) 15.0 (D) 163
Choose the correct answer from the options given below
(a) 0.00253 (b) 1.0003
(C) 15.0 (D) 163
Choose the correct answer from the options given below
A.
A, B and C only
B.
C and D only
C.
A, C and D only
D.
B and C only
JEE (Main) April 2023
Q10
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MCQ
The number of molecules and moles in 2.8375 litres of $O_{2}$ at STP are respectively
A.
$7.527 \times 10^{22}$ and 0.250 mol
B.
$1.505 \times 10^{23}$ and 0.250 mol
C.
$7.527 \times 10^{23}$ and 0.125 mol
D.
$7.527 \times 10^{22}$ and 0.125 mol
JEE (Main) April 2023
Q11
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MCQ
Match Column-I with Column-II
| Column-I | Column-II | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
A.
A-P, B-R, C-Q, D-S
B.
A-Q, B-R, C-S, D-P
C.
A-Q, B-S, C-R, D-P
D.
A-Q, B-D, C-P, D-R
JEE (Main) April 2023
Q12
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A metal chloride contains 55.0% of chlorine by weight. 100mL vapours of the metal chloride at STP weigh 0.57g. The molecular formula of the metal chloride is (Given: Atomic mass of chlorine is 35.5 u)
A.
$MCl_{2}$
B.
$MCl_{4}$
C.
$MCl_{3}$
D.
$MCl$
JEE (Main) April 2023
Q13
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In the given reaction cycle
X,Y and Z respectively are
X,Y and Z respectively are
A.
X Y Z
CaO NaCl + COā KCl
CaO NaCl + COā KCl
B.
X Y Z
CaCOā NaCl KCl
CaCOā NaCl KCl
C.
X Y Z
CaCOā NaCl HCl
CaCOā NaCl HCl
D.
X Y Z
CaO NaCl + COā NaCl
CaO NaCl + COā NaCl
JEE (Advanced) 2023
Q14
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JEE Section
Numerical
The stoichiometric reaction of 516 g of dimethyldichlorosilane with water results in a tetrameric cyclic product X in 75% yield. The weight (in g) of X obtained is ____
[Use, molar mass (g mol $^{-1}$ ):
H = 1, C = 12, O = 16, Si = 28, Cl = 35.5]
Correct Answer: 222
JEE (Main) June 2022
Q15
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MCQ
If a rocket runs on a fuel $(C_{15}H_{30})$ and liquid oxygen, the weight of oxygen required and $CO_{2}$ released for every litre of fuel respectively are
(Given : density of the fuel is 0.756 g/mL)
A.
1188 g and 1296 g
B.
2376 g and 2592 g
C.
2592 g and 2376 g
D.
3429 g and 3142 g
JEE (Main) June 2022
Q16
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MCQ
120 g of an organic compound that contains only carbon and hydrogen gives 330g of $CO_{2}$ and 270g of water on complete combustion. The percentage of carbon and hydrogen, respectively are
A.
25 and 75
B.
40 and 60
C.
60 and 40
D.
75 and 25
JEE (Main) June 2022
Q17
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A commercially sold conc. HCl is 35% HCl by mass. If the density of this commercial acid is 1.46 g/mL, the molarity of this solution is
(Atomic mass: Cl = 35.5 amu, H = 1 amu)
A.
10.2 M
B.
12.5 M
C.
14.0 M
D.
18.2 M
JEE (Main) June 2022
Q18
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Using the rules for significant figures, the correct answer for the expression $\frac{0.02858 \times 0.112}{0.5702}$ will be
A.
0.005613
B.
0.00561
C.
0.0056
D.
0.006
JEE (Main) July 2022
Q19
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MCQ
Which of the given reactions is not an example of disproportionation reaction
A.
$2H_{2}O_{2} \rightarrow 2H_{2}O + O_{2}$
B.
$2NO_{2} + H_{2}O \rightarrow HNO_{3} + HNO_{2}$
C.
$MnO_{4}^{-} + 4H^{+} + 3e^{-} \rightarrow MnO_{2} + 2H_{2}O$
D.
$3MnO_{4}^{2-} + 4H^{+} \rightarrow 2MnO_{4}^{-} + MnO_{2} + 2H_{2}O$
JEE (Main) July 2022
Q20
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Consider the reaction $4HNO_{3}(l) + 3KCl(s) \rightarrow Cl_{2}(g) + NOCl(g) + 2H_{2}O(g)$ $+3KNO_{3}(s)$
The amount of $HNO_{3}$ required to produce 110.0 g of $KNO_{3}$ is
(Given : Atomic masses of H,O,N and K are 1,16,14 and 39, respectively)
A.
32.2 g
B.
69.4 g
C.
91.5 g
D.
162.5 g
JEE (Advanced) 2022
Q21
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JEE Section
MSQ
To check the principle multiple proportion, a series of pure binary compounds $(P_mQ_n)$ were analyzed and their compositions is tabulated below. The correct option(s) (are)
| Compound | Weight % of P | Weight % of Q |
| 1 | 50 | 50 |
| 2 | 44.4 | 55.6 |
| 3 | 40 | 60 |
A.
If empirical formula of compound 3 is $P_{3}Q_{4}$ , then the empirical formula of compound 2 is $P_{3}Q_{5}$
B.
If empirical formula of compound 3 is $P_{3}Q_{2}$ , and atomic weight of element $P$ is 20, then the atomic weight of $Q$ is 45
C.
If empirical formula of compound 2 is $PQ$ , then the empirical formula of compound 1 is $P_5Q_4$
D.
If atomic weight of $P$ and $Q$ are 70 and 35, respectively, the empirical formula of compound 1 is $P_2Q$
JEE (Advanced) 2022
Q22
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Question Stem
Numerical
Dissolving 1.24 g of white phosphorous in boiling NaOH solution in an inert atmosphere gives a gas Q. The amount of $CuSO_{4}$ (in g) required to completely consume the gas Q is ____
[Given : Atomic mass of
$$
H = 1, O = 1 6, N a = 2 3, P = 3 1, S = 3 2, C u = 6 3 ]
$$
Correct Answer: 2.38
Explanation:
$P _ {4} \quad + 3 N a O H \longrightarrow P H _ {3} ^ {\prime} + 3 N a H _{2} PO _ {2}$
$\left(\frac {1.2 4}{1 2 4}\right)$ $0.01 mole$
$2 P H _ {3} + 3 C u ^ {2 +} \longrightarrow C u _ {3} P _ {2}$
$\left(\frac {1.2 4}{1 2 4}\right)$ $0.01 mole$
$2 P H _ {3} + 3 C u ^ {2 +} \longrightarrow C u _ {3} P _ {2}$
JEE (Main) March 2021
Q23
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Numerical
The exact volumes of 1M NaOH solution required to neutralize 50 mL of $1MH_{3}PO_{3}$ solution and 100 mL of $2MH_{3}PO_{2}$ solution, respectively, are
[a] 100 mL and 100 mL (b) 100 mL and 50 mL
(c) 100 mL and 200 mL (d) 50 mL and 50 mL
Correct Answer: C
Explanation:
$H_{3}PO_{3} + 2NaOH \rightarrow Na_{2}HPO_{3} + 2H_{2}O$ $50\,mL \quad 1M$ $1M \quad V = ?$ $\Rightarrow \frac{n_{NaOH}}{n_{H_{3}PO_{3}}} = \frac{2}{1}$ $\Rightarrow \frac{1 \times V}{50 \times 1} = \frac{2}{1} \Rightarrow V_{NaOH} = 100\,mL$ $H_{3}PO_{2} + 2NaOH \rightarrow NaH_{2}PO_{3} + H_{2}O$ $100\,mL \quad 1M$ $2M \quad V = ?$ $\Rightarrow \frac{n_{NaOH}}{n_{H_{3}PO_{3}}} = \frac{1}{1} \Rightarrow \frac{1 \times V}{2 \times 100} = \frac{1}{1} \Rightarrow V_{NaOH} = 200\,mL.$
JEE (Main) July 2021
Q24
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MCQ
The species given below that does NOT show disproportionation reaction is
A.
$BrO_{4}^{-}$
B.
$BrO^{-}$
C.
$BrO_{2}^{-}$
D.
$BrO_{3}^{-}$
JEE (Main) Aug. 2021
Q25
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MCQ
In which one of the following sets all species show disproportionation reaction
A.
$ClO_{2}^{-}, MnO_{4}^{-}$ and $CrO_{7}^{2-}$
B.
$MnO_{4}^{2-}, ClO_{2}^{-}$ and $Mn^{3+}$
C.
$ClO_{4}^{-}, MnO_{4}^{-}$ and $CrO_{2}^{-}$
D.
$Cr_{2}O_{7}^{2-}, MnO_{4}^{-}, ClO_{2}^{-}$ and $Cl_{2}$