Dalton's Atomic theory could not explain which of the following?
Some Basic Concepts in Chemistry
Every question from past board papers on Some Basic Concepts in Chemistry, newest paper first. Open any question for its full worked answer.
NEET UG 2025 question paper (official, booklet 45)
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Among the following, choose the ones with equal number of atoms.
A. 212 g of \(\mathrm{Na_2CO_3}\) (s) [molar mass = 106 g]
B. 248 g of \(\mathrm{Na_2O}\) (s) [molar mass = 62 g]
C. 240 g of NaOH (s) [molar mass = 40 g]
D. 12 g of \(\mathrm{H_2}\) (g) [molar mass = 2 g]
E. 220 g of \(\mathrm{CO_2}\)(g) [molar mass = 44 g]
Choose the correct answer from the options given below :
NEET UG 2024 question paper (official, booklet S6)
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1 gram of sodium hydroxide was treated with 25 mL of 0.75 M HCl solution, the mass of sodium hydroxide left unreacted is equal to
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The highest number of helium atoms is in
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A compound X contains 32% of A, 20% of B and remaining percentage of C. Then, the empirical formula of X is :
(Given atomic masses of A = 64; B = 40; C = 32 u)
NEET UG 2023 question paper (official, booklet G6)
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The right option for the mass of CO\(_2\) produced by heating 20 g of 20% pure limestone is (Atomic mass of Ca = 40)
\(\mathrm{CaCO_3 \xrightarrow{1200\ K} CaO + CO_2}\)
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Which amongst the following options is correct graphical representation of Boyle's Law?
(1) P vs T, straight lines through origin labelled V\(_1\), V\(_2\), V\(_3\) with V\(_1\)<V\(_2\)<V\(_3\); (2) P vs V, hyperbolas labelled T\(_1\), T\(_2\), T\(_3\) with T\(_3\)>T\(_2\)>T\(_1\); (3) P vs 1/V, straight lines labelled T\(_3\), T\(_2\), T\(_1\) with T\(_3\)>T\(_2\)>T\(_1\); (4) P vs 1/V, hyperbolic curves labelled T\(_3\), T\(_2\), T\(_1\) with T\(_3\)>T\(_2\)>T\(_1\).
NEET UG 2022 question paper (official, booklet R6)
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What mass of 95% pure \(CaCO_3\) will be required to neutralise 50 mL of 0.5 M HCl solution according to the following reaction ?
\(CaCO_{3(s)} + 2HCl_{(aq)} \to CaCl_{2(aq)} + CO_{2(g)} + 2H_2O_{(l)}\)
[Calculate upto second place of decimal point]
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Which one is not correct mathematical equation for Dalton's Law of partial pressure ? Here \(p\) = total pressure of gaseous mixture
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A 10.0 L flask contains 64 g of oxygen at 27°C. (Assume \(O_2\) gas is behaving ideally). The pressure inside the flask in bar is
(Given R = 0.0831 L bar \(K^{-1}\) \(mol^{-1}\))
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Copper crystallises in fcc unit cell with cell edge length of \(3.608 \times 10^{-8}\) cm. The density of copper is 8.92 g \(cm^{-3}\). Calculate the atomic mass of copper.
NEET UG 2021 question paper (official, booklet M4)
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Tritium, a radioactive isotope of hydrogen, emits which of the following particles ?
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Choose the correct option for the total pressure (in atm.) in a mixture of 4 g \(O_2\) and 2 g \(H_2\) confined in a total volume of one litre at \(0^\circ C\) is :
[Given R=0.082 L atm mol\(^{-1}\)K\(^{-1}\), T=273 K]
NEET UG 2020 question paper (official, booklet E1)
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Which one of the followings has maximum number of atoms ?
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The number of protons, neutrons and electrons in \(^{175}_{71}\)Lu, respectively, are :
NEET UG 2019 question paper (official, booklet P1)
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The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber's process is :
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A gas at 350 K and 15 bar has molar volume 20 percent smaller than that for an ideal gas under the same conditions. The correct option about the gas and its compressibility factor (Z) is :
NEET UG 2018 question paper (official, booklet EE)
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In which case is the number of molecules of water maximum ?
NEET UG 2016 Phase 1 question paper (official, booklet A)
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Lithium has a bcc structure. Its density is \(530\ kg\ m^{-3}\) and its atomic mass is \(6.94\ g\ mol^{-1}\). Calculate the edge length of a unit cell of Lithium metal. (\(N_A = 6.02\times10^{23}\ mol^{-1}\))
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Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape ?
NEET UG 2016 Phase 2 question paper (official, booklet ZZ)
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Suppose the elements X and Y combine to form two compounds \(XY_2\) and \(X_3Y_2\). When \(0.1\) mole of \(XY_2\) weighs \(10\) g and \(0.05\) mole of \(X_3Y_2\) weighs \(9\) g, the atomic weights of X and Y are