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 statements about atoms of a metal is correct? They
readily accept electrons
are soft
are held together by covalent bond
are held together by a sea of electron cloud
Correct answer is D
Metals are effectively lots of positively charged ions with a cloud/sea of delocalised electrons. This means the electrons are free to move throughout the metal, and is also why metals can conduct electricity as the electrons can move. The more delocalised electrons a metal has, the stronger it will be held together.
An oxide has the following properties. It
I. is a white powder
II. reacts with HCI.
III. reacts with NaOH
IV. is insoluble in water
The oxide is
alkaline
amphoteric
acidic
neutral
Correct answer is B
An amphoteric oxide is an oxide that can act as either an acid or base in a reaction to produce a salt and water.
The electron configuration of carbon atom in its excited state is
1s22s22px22py0
1s22s22px12py1
1s22s12px12py12pz1
1s12s22px12py1
Correct answer is C
- So any electron configuration in which the last electron (again, the valence electron) is in a higher energy orbital, this element is said to be in an excited state.
- When a carbon atom becomes excited by absorbing energy, one of its 2s electrons is promoted into the 2p sublevel.
Which of the following properties indicate that an element is a metal. It
I. reacts with oxygen to form an acidic oxide
II. forms ionic chlorides
III. has variable oxidation states
IV. displaces hydrogen from dilute HCl
I and III only
I and II only
II and IV only
I, II, III and IV
Correct answer is C
- Ionization behaviour; The atoms of non-metals usually have four to seven valence electrons. They have a great tendency to ionize by accepting electrons to form negative ions.
- Reaction with acids; A metal which is more electro positive than hydrogen readily displaces the hydrogen ion, H+, from an acid.
Ionization energy increases across the period in the periodic table because
atomic number increases
effective nuclear charge increases
mass number decreases
screening effect decreases
Correct answer is B
As the nuclear charge increases, its attraction for the outermost electron increases and so more energy is required to remove the outermost electron. Hence, the ionization energy increases.