Question
A substance, $X$, has the following properties.
1 It has a high melting point.
2 It conducts electricity in the solid and liquid states.
3 It is malleable.
4 It has a high density.
What is $X$ ?
A a ceramic
B copper
C graphite
D sodium chloride
▶️Answer/Explanation
Ans:B
These are properties of metals. Copper is a metal.
Question
Which property is shown by all metals?
A They are extracted from their ores by heating with carbon.
B They conduct electricity.
C They form acidic oxides.
D They react with hydrochloric acid to form hydrogen.
▶️Answer/Explanation
Ans:C
Metals form acidic oxides.
Question
Some properties of metal J are listed.
● J does not react with cold water.
● J reacts with dilute hydrochloric acid.
● No reaction occurs when the oxide of J is heated with carbon.
What is J?
A copper
B iron
C magnesium
D sodium
▶️Answer/Explanation
Ans: C
Magnesium (Mg) is generally considered to be unreactive with cold water. Unlike alkali metals (e.g., sodium and potassium), which vigorously react with cold water to produce hydrogen gas and the corresponding metal hydroxide, magnesium does not display such reactivity.
Magnesium does react with dilute hydrochloric acid (HCl). The reaction produces magnesium chloride and hydrogen gas.
The thermite reaction between magnesium oxide (MgO) and carbon (C), does not occur. In thermite reactions, a metal oxide reacts with a more reactive metal (like aluminum) or a reducing agent (like carbon) to produce molten metal and a gaseous oxide. However, magnesium oxide and carbon do not react in this way.
Question
Element X is in Group II of the Periodic Table.
Which statements about X are correct?
1 X is a metal.
2 X has two electrons in its outer shell.
3 X is a liquid at room temperature.
A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3
▶️Answer/Explanation
Ans: A
The alkaline earth metals are the elements found in Group 2 of the periodic table.
All of these elements have two electrons in their outermost electron shell, which is known as the valence shell.
Alkaline earth metals are not liquids; they are solid metals at room temperature.
Question
Which row describes magnesium?
▶️Answer/Explanation
Ans: D
Mg being a metal, has high electrical conductivity.
Magnesium does react with dilute acid, say, hydrochloric acid (HCl). The reaction produces magnesium chloride and hydrogen gas.