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.
Which of the following methods can be used to seperate blood cells from plasma?
Centrifugation
Filtration
Chromatography
Distillation
Correct answer is A
No explanation has been provided for this answer.
+2 to +3
0 to +2
+3 to +2
+3 to 0
Correct answer is C
The oxidation number of Iron in \(FeCl_{3}\) = +3. The oxidation number in \(FeCl_{2}\) = +2.
The empirical formula of a compound containing 0.067mol Cu and 0.066mol O is [Cu = 63.5, O = 16]
\(Cu_{2}O\)
\(CuO\)
\(CuO_{2}\)
\(CuO_{4}\)
Correct answer is B
Cu : O
0.067 : 0.066
mole ratio \(\frac{0.067}{0.066}\) : \(\frac{0.066}{0.066}\)
= 1 : 1
= CuO
oxidised
reduced
decomposed
dissociated
Correct answer is A
Reaction: \(2AgNO_{3} + Zn \to Zn(NO_{3})_{2} + 2Ag\)
The oxidation number of Zn in the reactant is 0, and in the product is +2. Therefor, it is oxidized.
The strength of metallic bonds depends on the
charge density of the atoms
ductility of the metal
number of valence electrons
total number of electrons in the atom
Correct answer is C
It is determined by the difference in the electron structures of the atoms. These primarily are: The number of outer electrons, i.e the number of valence shell electrons released during a metallic bond.
How many atoms are contained in 0.2moles of nitrogen? \([N_{A} = 6.02 \times 10^{23}]\)
\(1.20 \times 10^{23}\)
\(2.41 \times 10^{23}\)
\(3.62 \times 10^{23}\)
\(4.82 \times 10^{23}\)
Correct answer is A
\(1 mole = 6.02 \times 10^{23} atoms\)
\(0.2 moles = 6.02 \times 10^{23} \times 0.2\) atoms
= \(1.204 \times 10^{23}\)
\(\approxeq 1.2 \times 10^{23}\)
When chlorine is passed through a sample of water, the pH of the water sample would be
< 7
> 7
= 7
0
Correct answer is A
\(Cl_{2} + H_{2}O \to HCl + HOCl\)
The two compounds in the product end are acidic and hence, their mixture is acidic. Hence, the pH is < 7
One of the criteria for confirming the purity of benzene is to determine its
heat capacity
boiling point
mass
colour
Correct answer is B
Any pure substance will have a specific melting and boiling point. The presence of impurities alters the boiling point of benzene.
Which of the following CANNOT be an empirical formula?
\(CH\)
\(CH_{2}\)
\(P_{2}O_{5}\)
\(N_{2}O_{4}\)
Correct answer is D
The empirical formula is always in the ratio of the smallest positive integer, hence, \(N_{2}O_{4}\) has an empirical formula \(NO_{2}\)
\(Cu\) and \(HNO_{3}\) are not suitable for preparing hydrogen gas because of their
reactivity and oxidation respectively
conductivity and corrosiveness respectively
melting point and reduction respectively
electronegativity and solubility respectively
Correct answer is A
Copper is not active enough to replace hydrogen in an acid. Also, nitric acid is a strong oxidizing agent which quickly oxidises hygrogen to water.
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