Chemistry Class 9th

21. When a molecules consists of atoms of same element, it is called ______

A.Heteroatomic molecule

B. Homo atomic molecule

C. Atomic molecule

D. Poly atomic molecule

22. When a molecules consists of atoms of different elements, it is called ______

A. Heteroatomic molecule

B. Poly atomic molecule

C. Mono atomic molecule

D. Tri atomic molecule

23. Avogradro’s number is defined as the number of particles in one mole of any substance and is numerically equal to ______

A. 6.029*1023

B. 6.024*1023

C. 6.026*1023

D. 6.023*1023

24. Number was determined by an Italian scientist_______

A. Amedo

B. Amedo avogadro

C. Avogadro

D. None of these

25. Avogadro’s number represented by _______

A. “NA”

B. “H”

C. “O”

D. None of these

26. Chemists use a counting unit called _______

A. Mole

B. Ion

C. Atom

D. Molecule

27. _______ is defined as the amount of substance which contains Avagdro”s number.

A. Atom

B. Mole

C. Micromolecule

D. Poly atomic molecule

28. Mole is represented as _______

A. “m”

B. “mol”

C. A and B both

D. None of these

29. When the relative atomic mass is expressed in the ______

A. Gram atomic mass

B. Atomic molecule

C. Micromolecule

D. Poly atomic molecule

30. When the formula mass of an ionic compound is expressed in grams, it is called _______

A. Gram formula mass or gram formula

B. Mono atomic molecule

C. Atomic molecule

D. Micromolecule

31. Which one of the following groups comprise of elements:

A. Mercury, water, ammonia

B. Iodine, Tin, Iron

C. Copper, Aluminum, Methane

D. Coal, Smoke, Fog

32. The gram moleculer mass of HNO3 is:

A.60

B. 100

C. 63

D. 98

33. Which of these molecules is not a compound:

A. N2O

B. N2

C. NO

D. NO2

34.Which of the following is equal to two moles of water (H2O):

A. 1.08481025 molecules

B. 6.022*1023 molecules

C. 1.204*1024 molecules

D. 1.806*1024 molecules

35. A compound contains:

A. Different kinds of atoms mixed together

B. The same kinds of atoms mixed together

C. Different kinds of atoms chemically combined together

D. The same kinds of atoms chemically combined together

36. Which one of the following is an example of triatomic molecule:

A. CO2

B. O2

C. CH4

D. NH3

37. Hydrogen gas is:

A.  Monoatomic gas

B. A mixture of hydrogen atoms

C. A diatomic gas which each molecule made up of two atoms

D. A diatomic atom made up of two molecules

38. Which one of the following compounds has both empirical and molecular formula identical?

A. benzene (C6H6)

B. Hydrogen per oxide (H2O2)

C. Water (H2O)

D. glucose (C6H12O6)

39. Which one of the following is a homogeneous mixture

A. Smoke

B. Air

C. Fog

D. Smog

40. When the relative atomic mass is expressed in the ______

A. Gram atomic mass

B. Atomic molecule

C. Micromolecule

D. Poly atomic molecule