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.
How many electrons does \({31}_{15}\)P\(^3-\) contain?
12
15
16
18
Correct answer is D
- Phosphorus also has 15 electrons.
- Here we have P3- which means that this atom has gained 3 electrons. So, P3- has 18 electrons.
heating to saturation and drying
filtering and evaporation to dryness
filtering, washing and drying
crystallizing and allowing to cool
Correct answer is C
No explanation has been provided for this answer.
The metallic bond in magnesium is stronger than that in calcium because magnesium has a
larger atomic size.
smaller atomic size
greater number of valence electrons
lower melting point
Correct answer is B
- Magnessium has a stronger metallic bond than calcium because it has smaller atomic radius.
- Atomic radius decreases across a period and increases down a group.
Which of the following arrangement of elements is in decreasing order of electronegativity?
Na, Mg, Al, Si, P
Na, A1, Mg, P, Si
P, Mg, Na, Si, Al
P, Si, Al, Mg, Na
Correct answer is D
- Reactivity series is K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au.
-Very Electropositive Metals Most active metals have low electronegativities
Which of the following metals does not react with water to produce hydrogen?
Copper
Potassium
Sodium
Zinc
Correct answer is A
Most alkali metals and alkaline earth metals react with water to produce hydrogen. The alkali metals comprise Group 1 of the periodic table, and include lithium, sodium, potassium, etc.
- Zinc is not much reactive with cold or room temperature water but reacts with steam to form zinc oxide and liberate hydrogen gas.
- Copper lies below hydrogen in the activity series of metals, therefore it can not displace hydrogen from water