Tag: chemical properties of metals

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Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

When a small piece of dry sodium is put in water, it reacts vigorously to produce:

  1. nitrogen gas

  2. hydrogen gas

  3. carbon dioxide gas

  4. sulphur dioxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Most of the metals do not react with water. However,alkali metals react vigorously with water. Reaction of sodium metal with water: Sodium metal forms sodium hydroxide and liberates hydrogen gas along with lot of heat when reacts with water.
 When sodium reacts with water, sodium hydroxide is formed hydrogen gas as a byproduct that gets burnt with a bright flame making the reaction highly exothermic.
  
Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

The incorrect statement among the following for magnesium metal is:

  1. it burns in oxygen with dazzling white flame

  2. tt reacts with cold water to form magnesium oxide and evolves hydrogen gas

  3. it reacts with hot water to form magnesium hydroxide and evolves hydrogen gas

  4. it reacts with steams to form magnesium hydroxide and evolves hydrogen gas
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Magnesium burns in steam to produce white magnesium oxide and hydrogen gas. If a metal reacts with cold water the metal hydroxide is formed but if it reacts with steam the metal oxide is formed.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

$2Fe(s) + 3H _2O(g)\rightarrow$

  1. $Fe _2O(s) + 3H _2(g)$
  2. $Fe _2O _3(s) + 3H _2(g)$
  3. $Fe _2O _3(s) + 3H _2O(g)$

  4. None of above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron is less reactive than sodium, potassium, calcium, zinc and magnesium. It does not react with cold and hot water, but it reacts with steam to form magnetic oxides.
$ 2Fe(s) + 3H _2O(g) \rightarrow Fe _2O _3(s) + 3H _2(g) $

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

In case of reaction between sodium and cold water, hydrogen burns with _______ flame, whereas, in case of reaction between potassium and cold water, hydrogen burns with _____ color.

  1. Yellow, lilac

  2. Orange, yellow

  3. Orange, lilac

  4. Lilac, yellow
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When sodium is added to water, the sodium melts to form a ball that moves around on the surface. It fizzes rapidly, and the hydrogen produced may burn with an orange flame before the sodium disappears.When potassium is added to water, the metal melts and floats. The hydrogen ignites instantly. The metal is also set on fire, with sparks and a lilac flame. 

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

The reaction of sodium metal with cold water is

  1. Endothermic

  2. Exothermic

  3. Both a and b

  4. Neither a nor b
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Metals like sodium and potassium react violently with cold water. These reactions are exothermic. The reaction is so violent and exothermic that the hydrogen which is evolved immediately catches fire.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

Which of the following exists as cations with delocalized electrons?

  1. Non-polar covalent substance

  2. Polar covalent substance

  3. Ionic substance

  4. Metallic substance

  5. Noble gas
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Metallic substance exists as cations with delocalized electrons.
The positive ions (cations) are arranged to form a kernel in the sea of delocalised electrons. The force of attraction between the positive ions (cations)  and  the sea of delocalised electrons is called the metallic bond.