ECAT Chemistry Chapter 1 Basic Concepts

He Ar and Ne are:

• Mono-atomic molecules A

• Hetero atomic molecules

  B

• Poly-atomic molecules

  C

• Diatomic molecules

  D

The branch of science dealing with structure, composition and changes in matter and laws and principles which govern these changes is called as

• chesmistry A
• Geology B
• Physics C
• Mechanics D

In molecules kinetic and potential energies are:

• Definite A
• Moderate B
• Indefinite C
• None of above 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

Al³⁺is a symbol for aluminium

• Atom A
• Ion B
• Cation C
• Anion D

The empirical formula of a compound is CH₂O. What may be the compound

• C₂H₅OH A
• C₆H₅OH B
• HCOOH C
• 
  D

The wave length of visible light is 500 nm. In S.I. unit this value is

• 5 x 10^-8m A
• 5 x 10^-9m B
• 500 x 10^-7m C
• 500 x 10^-9m D

Objects of the size of an atom can be observed in

• An electron microscope A
• An x-ray spectrum B
• Atomic absorption spectrum C
• A visible spectrum D

How many moles of hydrogen atoms does 3.2 g of methane, CH₄, contain?

• 0.02 A
• 0.2 B
• 0.4 C
• 0.8 D

Mass spectrometer measures the

• Exact mass of an element A
• Average mass of an element B
• The number of elements present in a molecule C
• m/e value of a positive ion D

A beaker contains 9 grams of water. The number of H-atoms is

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

The mass of sulphur which combines with 24 grams oxygen to form SO₂

• 32 gram A
• 24 gram B
• 8 gram C
• 12 gram D

One mole of ethanol and one mole of ethane have an equal

• Mass A
• Number of atoms B
• Number of electrons C
• Number of molecules D

Which statement about an atom is true ?

• The number of neutrons is not equal to number of electrons A
• Mass number is less than atomic number B
• All the elements have only one mass number C
• Mass number can be equal to atomic number D

A compound contains one atom of oxygen and % of O 34.78, then molecular mass of compound is

• 46 A
• 78 B
• 110 C
• 180 D

A molecular ion is formed by

• Passing a high energy electron beam through gaseous molecule A
• Dissolving a salt i dilute acid B
• Passing electric current through molten salt C
• Passing electricity through aqueous solutions D

Which of the sub-atomic particles is not charged

• Electron A
• Proton B
• Neutron C
• All of them D

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

The number of moles of CO2which contain 8.0 g of oxygen

• 0.25 A
• 0.50 B
• 1.0 C
• 1.50 D

Which one of the following compounds does not have the empirical formula CH₂O?

• Ethanoic acid, CH₃CO₂H A
• Ethanol, CH₃CH₂OH B
• Glucose, C₆H₁₂O₆ C
• Methanal, HCHO 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

Each molecule of haemoglobin is 68000 times heavier than one atom of

• C A
• H B
• N C
• O 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

Which statement about molecule is incorrect ?

• Molecules of a substance are similar A
• Hemoglobin is a homo atomic molecules B
• Oxygen molecule is a macro molecule C
• It exist independently D

If four moles of sulpur dioxide are oxidised to sulphur trioxide, how many moles of oxygen molecules are required

• 0.5 A
• 1.0 B
• 1.5 C
• 2.0 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

A limiting reactant is the one which

• Is taken in lesser quantity in grams as compared to other reactants A
• Is taken in lesser quantity in volume as compared to other reactants B
• Gives the maximum amount of the product which is required C
• Gives the minimum amount of the product under consideration D

Covalent compound s mostly exist in the form of:

• Protons

  A

• Atoms

  B
• Neutrons C

• Molecules

  D

Isotopes differ in

• properties which depend upon mass A
• arrangement of electrons in orbitals B
• chemical properties C
• the extent to which they may be affected in electric fields D

The atomic mass is measured in atomic mass unit (a.m.u.) which is equal to

• 1.661 x 10^{-27- Kg} A
• 1.661 x 10^-24Kg B
• 1.661 x 10^{-27- g} C
• 1.661 x 10^-24mg D