Chemistry

Some Basic Concepts of Chemistry

Question:

How much copper can be obtained from 100 g of copper sulphate (CuSO4  )? (Atomic mass of Cu= 63.5 amu)

Answer:

1 mole of  CuS04  contains 1 mole (1 g atom) of Cu

Molar mass of  CuS04= 63.5 + 32 + 4 x 16 = 159.5 g  mol-1

Thus, Cu that can be obtained from 159.5 g of  CuS04  = 63.5 g

ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-7

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Some Basic Concepts of Chemistry

Q 1.

How many oxygen atoms are there in 18 g of water?

Q 2.

How much copper can be obtained from 100 g of copper sulphate (CuSO4  )? (Atomic mass of Cu= 63.5 amu)

Q 3.

Match the following prefixes with their multiples:
ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-15

Q 4.

What do you understand by stoichiometric coefficients in a chemical equation?

Q 5.

State Avogadro’s law.

Q 7.

Define the term ‘unit’ of measurement.

Q 8.

What is one a.m.u. or one ‘u’?

Q 9.

Round up the following upto three significant figures:
(i) 34.216 (ii) 10.4107 (iii) 0.04597 (iv) 2808

Q 10.

What do you mean by significant figures?

Q 11.

Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.

Q 12.

Define molality. How does molality depend on temperature?

Q 13.

Name two factors that introduce uncertainty into measured figures.

Q 14.

Calculate the atomic mass (average) of chlorine using the following data:
ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-9

Q 15.

Pressure is determined as force per unit area of the surface. The S.I. unit of pressure, pascal, is as shown below:1 Pa = 1  Nm-2.If mass of air at sea level is 1034 g  cm-2,calculate the pressure in pascal.

Q 16.

In the reaction, A + B2——> AB2, identify the limiting reagent, if any, in the following  mixtures
(i) 300 atoms of A + 200 molecules ofB
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules ofB
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B

Q 17.

The density of water at room temperature is 1.0 g/mL. How many molecules are there in a drop of water if its volume is 0.05 mL?

Q 18.

Calculate the mass of sodium acetate (CH3COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g  mol-1

Q 19.

How are 0.50 mol  Na2C03  and 0.50 M  Na2C03  different?

Q 20.

What is the molecular mass of a substance each molecule of which contains 9 atoms of carbon, 13 atoms of hydrogen and 2.33 x  10-23  g other component?

Q 21.

Express the following up to four significant figures.
ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-38

Q 22.

Q 23.

Chlorine is prepared in the laboratory by treating manganese dioxide (Mn02) with aqueous hydrochloric acid according to the reaction.
4 HCl (aq) + Mn02 (s) ———–> 2 H2O (l) + MnCl2(aq) +Cl2(g)

How many grams of HCl react with 5.0 g of manganese dioxide? (Atomic mass of Mn = 55 u)

Q 24.

Why air is not always regarded as homogeneous mixture?

Q 25.

Calculate the molecular mass of the following:
(i)  H20(ii)  C02(iii)  CH4

Q 26.

Give an example of a molecule in which the ratio of the molecular formula is six times the empirical formula.

Q 27.

Express the following in scientific notation:
(i) 0.0048 (v) 6.0012 (ii) 234,000 (iii) 8008 (iv) 500.0

Q 28.

If ten volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour could be produced?

Q 29.

Calculate the concentration of nitric acid in moles per litre in a sample which has a density 1.41 g  mL-1  and the mass percent of nitric acid in it is being 69%.

Q 30.

What is the number of significant figures in 1.050 x 104?

Q 31.

Calculate the mass percent of different elements present in sodium sulphate (Na2 SO4).

Q 32.

The cost of table salt (NaCl) and table sugar (C12H22O11) are Rs 1 per kg and Rs 6 per kg respectively.Calculate their cost per mole.

Q 33.

What is the S.I. unit of mass?

Q 34.

Calculate no. of carbon and oxygen atoms present in 11.2 litres of  C02  at N.T.P.

Q 35.

A flask P contains 0.5 mole of oxygen gas. Another flask Q contains 0.4 mole of ozone gas. Which of the two flasks contains greater number of oxygen atoms?

Q 36.

What is the SI unit of molarity?

Q 37.

Use the data given in the following table to calculate the molar mass of naturally occurring argon.
ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-30

Q 38.

A sample of drinking water was found to be severely contaminated with chloroform, CHCly supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).
(i) Express this in percent by mass
(ii) Determine the molality of chloroform in the water sample.

Q 39.

Determine the empirical formula of an oxide of Iron which has 69.9 % iron and 30.1 % dioxygen by mass.

Q 40.

How is empirical formula of a compound related to its molecular formula?

Q 41.

The following data were obtained when dinitrogen and dioxygen react together to form compounds:
ncert-solutions-for-class-11-chemistry-chapter-1-some-basic-concepts-of-chemistry-19

Q 42.

If the density of methanol is 0.793 kg  L -1, what is its volume needed for making 2.5 L of its 0.25 M solution?

Q 43.

Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation:(i)  N2 (g) + 3H2(g) —–> 2NH3 (g)
(ii) Will any of the two reactants remain unreacted?
(iii) If yes, which one and what would be its mass?

Q 44.

How are 0.5 ml of NaOH differents from 0.5 M of NaOH?

Q 45.

10 ml of a solution of NaCl containing KCl gave on evaporation 0.93 g of the mixed salt which gave 1.865 g of AgCl by reacting with  AgN03solution. Calculate the quantity of NaCl in 10 mL of the solution.

Q 46.

Which one of the following will have largest number of atoms?
(i) 1 g Au (s) (ii) 1 g Na (s) (iii) 1 g Li (s) (iv) 1 g of  Cl2(g)  (Atomic masses: Au = 197, Na = 23, Li = 7, Cl = 35.5 amu)

Q 47.

Calculate the number of atoms in each of the following:
(i) 52 moles of He (ii) 52 u of He (iii) 52 g of He

Q 48.

Calcium carbonate reacts with aqueous HCl according to the reaction

CaC03 (s) + 2HCl (aq) ———->CaCl2  (aq) +C02(g) +H2O(l).

What mass of CaC03 is required to react completely with 25 mL of 0.75 M HCl?

Q 49.

What is an atom according to Dalton’s atomic theory?

Q 50.

Convert 2.6 minutes in seconds.