Chemistry Past Questions and Answers

The electronic configuration of an elements is 1s²2s²2p⁶3s²3p³. How many unpaired electrons are there in the element?

Question 12:

The ions X_- and Y₊ are isoelectronic, each containing a total of 10 electrons.
How many protons are in the nuclei of the neutral atoms of X and Y respectively?

A 10 and 10
B 9 and 9
C 11 and 9
D 9 and 11

Question 13:

Which of the following represents the type of bonding present in ammonium chloride molecule?

A Ionic only
B Covalent only
C Ionic and dative covalent
D Dative covalent only

Question 14:

Which of the following is arranged in order of increasing electronegativity?

A Chlorine, aluminium, magnesium, phosphorus, sodium
B Sodium, magnesium, aluminium, phosphorus, chlorine
C Chlorine, phosphorus, phosphorous, aluminium, magnesium, sodium
D Sodium, chlorine, phosphorus, magnesium, aluminium

Question 15:

A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of?

A Nitrogen
B Neon
C Argon
D Oxygen