19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
If 1021 molecules are removed from 200mg of CO2, then the number of moles of CO2 left are
Assertion :Pure water obtained from different states of India always contains hydrogen and oxygen in the ratio of 1 : 8 by mass. Reason: Total mass of reactants and products during chemical change is always the …
The largest number of molecules is in
The number of water molecules present in a drop of water (volume = 0.0018 ml) at room temperature is (density of H2O = 1 g/mL)
A sample of calcium carbonate (CaCO3) has the following percentage composition: Ca = 40%, C = 12%, O = 48%. If the law of constant proportions is true, then the weight of calcium in 4g of a s…
The law of conservation of mass holds good for all of the following except:
3 g of a hydrocarbon on combustion in excess of oxygen produces 8.8g of CO2 and 5.4 g of H2O. The data illustrates the law of:
Zinc sulphate contains 22.65% Zn and 43.9% H2O. If the law of constant proportions is true, then the mass of zinc required to give 40g crystals will be :
Which of the following reaction is not according to the law of conservation of mass
A 27.0 g sample of an unknown hydrocarbon was burned in excess O2 to form 88g of CO2 and 27g of H2O. What is possible molecular formula of hydrocarbon ?
The total number of electrons present in 18 ml of water (density of water is 1 g ml–1) is
Number of atoms in 560g of Fe (atomic mass 56 g mol–1) is
If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will
P and Q are two elements which forms P2Q3 and PQ2. If 0.15 mole of P2Q3 weights 15.9g and 0.15 mole of PQ2 weights 9.3g, the atomic weight of P and Q is (respectively) :
100 mL of mixture of NaOH and Na2SO4 is neutralised by 10 mL of 0.5 M H2SO4. Hence, NaOH in 100 mL solution is
In one molal solution that contains 0.5 mole of a solute, there is (NEET 2022)
What mass of 95% pure CaCO3 will be required to neutralise 50 mL of 0.5 M HCl solution according to the following reaction? CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + 2H2O(l) [Calculate upto second place of decimal po…
An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is: [Atomic wt. of C is 12, H is 1] (NEET 2021)
Which one of the following has maximum number of atoms? (NEET 2020)
The density of 2 M aqueous solution of NaOH is 1.28 g/cm3. The molality of the solution is [Given that molecular mass of NaOH = 40 g mol–1] (Odisha NEET 2019)
The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is (NEET 2019)
In which case is number of molecules of water maximum? (NEET 2018)
Which of the following is dependent on temperature? (NEET 2017)
Suppose elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mol of XY2 weighs 10g and 0.05 mol of X3Y2 weighs 9g, the atomic weights of X and Y are (NEET 2016)
What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO3 is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5) (NEET 2015)