Some Basic Concepts of Chemistry

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The empirical formula of a compound is CH2O. Its molecular weight is 180. The molecular formula of compound is:

 
 
 
 

0.4 moles of HCl and 0.2 moles of CaCl2 were dissolved in water to have 500 mL of solution, the molarity of Cl ion is:

 
 
 
 

If the true value for an experimental result is 6.23 and the results reported by three students X, Y, Z are:
X: 6.18 and 6.28
Y: 6.20 and 6.023
Z: 6.22 and 6.24
Which of the following option is correct:

 
 
 
 

Which has the maximum number of molecules among the following?

 
 
 
 

Which of the following pairs of solutions are expected to be isotonic, temperature being the same?

 
 
 
 

Arrange the following in the order of increasing mass (atomic mass: O = 16, Cu = 63, N = 14)
I. one atom of oxygen
II. one atom of nitrogen
III. 1 × 10–10 mole of oxygen
IV. 1 × 10–10 mole of copper

 
 
 
 

The molar concentration of 20 g of NaOH present in 5 litre of solution is:

 
 
 
 

Which one of the following is the lightest?

 
 
 
 

Volume of water needed to mix with 10 mL 10N HNO3 to get 0.1 N HNO3 is:

 
 
 
 

1021 molecules are removed from 200 mg of CO2. The moles of CO2 left are :

 
 
 
 

Temperature does not affect:

 
 
 
 

The oxide of an element contains 67.67% oxygen and the vapour density of its volatile chloride is 79. Equivalent weight of the element is:

 
 
 
 

1 cc. N2O at NTP contains:

 
 
 
 

A solution is prepared by dissolving 24.5 g of sodium hydroxide in distilled water to give 1 L solution. The molarity of NaOH in the solution is
(Given that molar mass of NaOH = 40.0 g mol–1)

 
 
 
 

The number of atoms in 0.1 mole of a triatomic gas is:
(NA = 6.02×1023 mol–1)

 
 
 
 

The weight of one molecule of a compound of molecular formula C60H122 is

 
 
 
 

60 gm of an organic compound on analysis is found to have C = 24 g, H = 4 g and O = 32 g. The empirical formula of compound is:

 
 
 
 

The weight of a single atom of oxygen is:

 
 
 
 

The number of moles of oxygen in one litre of air containing 21% oxygen by volume, tmder standard conditions are

 
 
 
 

The simplest formula of a compound containing 50% of element X (atomic mass 10) and 50% of element Y (atomic mass 20) is

 
 
 
 

The reaction of calcium with water is represented by the equation
Ca + 2H2O → Ca(OH)2 + H2
What volume of H2 at STP would be liberated when 8 gm of calcium completely reacts with water?

 
 
 
 

In a hydrocarbon, mass ratio of hydrogen and carbon is 1:3, the empirical formula of hydrocarbon is

 
 
 
 

Sulphur forms the chlorides S2Cl2 and SCl2. The equivalent mass of sulphur in SCl2 is

 
 
 
 

If NA is Avogadro’s number then numberofvalenceelectrons in 4.2 g of nitride ions (N3–) is

 
 
 
 

3g of an oxide of a metal is converted to chloride completely and it yielded 5g of chloride. The equivalent weight of the metal is

 
 
 
 

Given the numbers: 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is

 
 
 
 

Match the cohunns

Column-I
(Number)
Column-II
(Significant figures)
A. 29900. I. 2
B. 290 II. 1
C. 1.23 × 1.331 III. 4
D. 20.00 IV. 3
E. 2.783–1 V. 5
 
 
 
 

For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be

 
 
 
 

The density of 3M solution of sodium chloride is 1.252 g mL–1. The molality of the solution will be:
(molar mass, NaCl = 58.5 g mol–1)

 
 
 
 

The maximum number of molecules are present in

 
 
 
 

Calculate the normality of 10 volume H2O2?

 
 
 
 

Calculate the millimoles of SeO32– in solution on the basis of following data:
70ml of M/60 solution of KBrO3 was added to SeO32– solution. The bromine evolved was removed by boiling and excess of KBrO3 was back titrated with 12.5 mL of M/25 solution of NaAsO2.
The reactions are given below.

I. SeO32– + BrO3 + H+ → SeO42– + Br2 + H2O
II. BrO3 + AsO2 + H2O → Br + AsO43– + H+

 
 
 
 

Match the columns

Column-I Column-II
A. 88g of CO2 I. 0.25 mole
B. 6.022 × 1023 molecules II. 2 mole of H2O
C. 5.6 litres of O2 at STP III. 1 mole
D. 96g of O2 IV. 6.022×1023 molecules
E. 1 mol of any gas V. 3 mole
 
 
 
 

The vapour density of a mixture containing NO2 and N2O4 is 27.6. Mole fraction of NO2 in the mixture is

 
 
 
 

KMnO4 reacts with oxalic acid according to the equation:

2MnO4 + 5C2O4 + 16H+ → 2Mn++ + 10CO2 + 8H2O
Here 20 mL of 0.1 M KMnO4 is equivalent to:

 
 
 
 

The molarity of H2SO4 solution, which has a density 1.84 g/cc. at 35° C and contains 98% by weight, is:

 
 
 
 

The normality of solution obtained by mixing (10ml of N/5 HCI) and (30 ml of N/10 HCl) is:

 
 
 
 

Number of grams of oxygen in 32.2g Na2SO4.10H2O is

 
 
 
 

The weight of NaCl decomposed by 4.9g of H2SO4, if 6 g of sodium hydrogen sulphate and 1.825 g of HCl, were produced in the reaction is:

 
 
 
 

Volume of a gas at NTP is 1.12 × 10–7 cc. The number of molecule in it is:

 
 
 
 

The normality of orthophosphoric acid having purity of 70% by weight and specific gravity 1.54 is:

 
 
 
 

One of the following combination which illustrates the law of reciprocal proportions?

 
 
 
 

During electrolysis of water the volume of O2 liberated is 2.24 dm3. The volume of hydrogen liberated, under same conditions will be

 
 
 
 

An aqueous solution of 6.3 g of oxalic acid dihydrate is made up to 250 ml. The volume of 0.1 N NaOH required to completely neutralise 10 ml of this solution is

 
 
 
 

The set of numerical coefficients that balances the equation
K2CrO4 + HCl → K2Cr2O7 + KCl + H2O is

 
 
 
 

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