ECAT Chemistry Chapter 1 Basic Concepts

Two different hydrocarbon each contain the same percentage by mass of hydrogen. It follows that they have the same

• Empirical formula A
• Number of atoms in a molecules B
• Number of isomers C
• Relative molecular mass D

A ring contains 3 gram diamond. The number of C-atoms which a ring contains is

• 3.01 x 10²³ A
• 1.5 x 10²³ B
• 6.02 x 10²⁴ C
• 3.01 x 10²⁴ D

The mass of Al₂S₃formed when 20 grams Al reacts completely with S is

• 60 g A
• 50 g B
• 50.55 g C
• 55.55 g D

The number of atoms present in molecule determines its:

• Molecularity A
• Atomicity B
• Basicity C
• Acidity D

The negatively charged particles are called

• Cation A
• Radical B
• Anion C
• Positron D

Ascorbic acid contains 40.92% carbon, 4.58%, hydrogen and 54.4% oxygen. The empirical formula is

• C₃H₄O₃ A
• C₂H₄O₃ B
• C₃H₅O₄ C
• C₂H₃O₁ D

The phenomenon of isotropy was first discovered by

• Soddy A
• Rutherford B
• Bohr C
• Dalton D

When 0.1 g of magnesium is treated with an excess of hydrochloric acid, what volume of gas at room temperature and pressure will be produced

• 10 cm³ A
• 25 cm³ B
• 48 cm³ C
• 100 cm³ D

• 300 cm³ A
• 200 cm³ B
• 150 cm³ C
• 100 cm³ D

Isotopes of an element differ in

• Number of protons A
• Number of electrons B
• Number of neutrons C
• Number of electrons and protons D

A molecule of haemoglobin is made up if nearly

• 10,000 atoms A
• 50,000 atoms B
• 2500 atoms C
• 1500 atoms D

Which one of the following step is not involved in determination of empirical formula

• Determination % of each element A
• Determination of gram atom of each element B
• Determination of isotopes of each element C
• Determination of atomic ratio of element D

How many moles of oxygen, O₂are needed for the complete combustion of two moles of butane C₄H₁₀?

• 2 A
• 8 B
• 10 C
• 13 D

• 99.2% A
• 99.5% B
• 90.5% C
• 96.2% D

One mole of SO₂contains

• 6.02 x 10²³atoms of oxygen A
• 18.1 x 10²³, molecules of SO₂ B
• 6.02 x 10²³ atoms of sulphur C
• 4 gram atoms of SO₂ D

• 0 dm³ A
• 3 dm³ B
• 2 dm³ C
• 3 dm³ D

• 32 g A
• 3.2 g B
• 5.6 g C
• 9.6 g D

Smallest particle of an element which may or may not have independent existence is known as:

• A molecule A
• An ion B
• An atom C
• An electron D

A limiting reactant is one which according to the stoichiometric equation

• Has excess mass A
• Has least mass B
• Has excess number of moles C
• Has least number of moles D

When an electron is added to a uni positive ion we get:

• Cation A
• Molecule B
• Neutral atom C
• Anion D

The atom of an element is

• The smallest particle A
• The fundamental particle B
• The independent particle C
• The charged particle D

The value of R(General Gas Constant) is

• 8.3134 JK^-1mole^-1

  A

• 1.987 Cal K^-1Mole^-1

  B
• Both a and b C

• 1.987 JK^-1mole^-1

  D

The isotopes of an element

• Possess same mass number A
• Possess same number of protons B
• Do not possess same chemical properties C
• May or may not possess same chemical properties D

The diameter of atoms is of the order:

• 2* 10^-5m A

• 2* 10^-10 m

  B
• 2* 10^-2m C
• 2* 10^-3m D

• 84.84 % A
• 89.89% B
• 81.81% C
• 90.90% D

The amount of products obtained from the balanced chemical equation is regarded as

• Theoretical yield A
• Actual yield B
• % yield C
• Experimental yield D

What is the volume in cm³of 3.01 x 10²³molecules of O₂gas at S.T.P

• 1000 cm³ A
• 11000 cm³ B
• 1120 cm³ C
• 11200 cm³ D

Which one of the following statements is not correct

• A molecule is the smallest particle of an element which can exist independently A
• He is a molecule of helium B
• S₈is a molecule of sulphur C
• O₃is a molecule of oxygen D

Al³⁺is a symbol for aluminium

• Atom A
• Ion B
• Cation C
• Anion D

A compound X contains 50% sulphur and 50% oxygen by mass. What is the empirical formula of compound X?

• SO A
• SO₂ B
• SO₃ C
• SO₄ D