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