25 questions
Which term defines a substance that is formed by the combination of elements using fixed amounts?
atom
compund
element
molecule
Which term defines any substance that cannot be broken down into a simpler substance?
atom
molecule
element
compound
Which of the following statements is not true about an atom?
Atoms are always neutral in nature
Atoms are not able to exist independently
Atoms are the basic units from which molecules and ions are formed
Atoms aggregate in large numbers to form the matter that we can see, feel or touch
The chemical symbol for nitrogen gas is
ni
N2
N
NI
The chemical symbol for sodium is
so
SO
Na
NA
Which of the following has maximum number of atoms?
18g of H2O
18g of O2
18g of CO2
18g of CH4
A change in the physical state can be brought about
only when energy is given to the system
only when energy is taken out from the system
when energy is either given to or taken out from the system
without any energy change
molecular formula of copper and bromine is
CuBr2
CUBR
Cu2Br
CuBr
Atomic number of oxygen is
4
6
8
12
valency of helium is
0
3
2
1
chemical formula of aluminium and hydrogen is
aLoH
Al(OH)3
AL(OH)2
AloH
Molecular mass is defined as the:
Mass of one molecule of any substance compared with the mass of one atom of C – 12
Mass of one atom compared with the mass of one atom of hydrogen
Mass of one atom compared with the mass of one molecule
none of these
Atomic mass of sodium is
13
23
21
19
Which of the following represents a correct chemical formula?
BiPO4
NaSO4
NaS
CaCl
to create a chemical formal you need to know
the atomic mass of an element
the mass of an element
valency of an element
all of these