Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
What volume of carbon (ll) oxide is produced by reacting excess carbon with 10 dm3 of oxygen?
5 dm 3
20 dm 3
15 dm 3
10 dm 3
Correct answer is B
No explanation has been provided for this answer.
The presence of an impurity in substance will cause the melting point to
be zero
reduce
increase
be stable
Correct answer is B
Impurities disrupt the repeating pattern of forces that holds the solid together. So a smaller amount of energy is required to melt the part of the solid surrounding the impurity. If less energy is required, then this explains the melting point depression (lowering) observed from impure solids. The more impure the solid is, the more the structure is disrupted and the greater the variation in intermolecular forces in different areas of the solid.
An element Z, contained 90% of 168Z and 10% of Z1818 its relative atomic mass is?
16.0
16.2
17.0
17.8
Correct answer is B
Mass number of Z = 16 while that of Z is 18
90 x 16 = 14.4 10 x 18 = 1.8
100 1 100 1
it relative atomic mass = 14.4 + 1.8 = 162
Neutrons 53, Protons 17
Neutrons 17, Protons 36
Neutrons 19, Protons 17
Neutrons 36, Protons 17
Correct answer is C
Mass number = number of protons + number of neutrons
36 = 17 + X; X = 36 -17 = 19
19 neutrons and 17 protons
r = k/√d
r = kd
r =k/d
r = k √d
Correct answer is A
r = k /√d