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.
NH3(g) + HCl(s) → NH 4Cl (s)
The entropy change in the system above is
positive
zero
negative
intermediate
Correct answer is C
Entropy s is a measure of the degree of disorder or randomness of a substance. The entropy charge in the system is negative. Options B, C, D will not give negative but the result into positive
When sugar is dissolve in tea, the reaction is accomplished by?
positive change
negative entropy change
no entropy change
a minimum entropy change
Correct answer is C
There is no disorderliness so no entropy change.
The elements that belong to the third period of periodic table are
Li, Be, Al and D
Na, P, O and Cl
B, C, N, and O
Na, Mg, S and Ar
Correct answer is D
Na, Mg, S and Ar is the set of elements that belong to third period of the periodic table. Option A,B,C have elements which belong to the other period in the periodic table included in them.
An oxidation state of Cr in K2Cr2O7
7
6
5
4
Correct answer is B
The oxidation state of K2Cr2O7 is +6. option A,C,D are the oxidation state of other elements like O7,C14, etc.
\(+2 + 2x + (-2\times7) =0\)
\(2x=12\)
\(x = +6\)
CH2O
C3H6O3
C6H12O6
C6H12O3
Correct answer is C
C = 40%, 40/12 = 3.33
H = 6.7%, 6.7/1 = 6.7
O = 53.3%, 53.3/16 = 3.33
C = 3.33/3.33 = 1
H = 6.7/3.33 = 2
O = 3.33/3.33 = 1
(CH2O)n = 180
(12 + 2 + 16)n = 180
30n = 180
n = 6
= C6H12O6