Tag: chemical properties of metals

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

Sodium in water catches fire due to formation of,

  1. hydrogen gas and evolution of heat.

  2. nitrogen gas and evolution of heat.

  3. hydrogen gas and absorption of heat.

  4. sulfur gas.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium in water catches fire due to formation of hydrogen gas and evolution of heat.
$\displaystyle 2Na + 2H _2O \rightarrow 2Na^+ + 2OH^- + H _2 \uparrow$
Note: In exothermic process, heat is released. The reaction of Na with water is highly exothermic. Due to rapid increase in temperature, hydrogen gas catches fire.

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

The reaction of potassium and water is ______ in nature.

  1. endothermic

  2. exothermic

  3. electron donating

  4. electron withdrawing
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reaction of potassium and water is  exothermic in nature.
Potassium explosively reacts with water to form KOH with evolution of hydrogen gas.
$\displaystyle 2K + 2H _2O \rightarrow 2K^+ + 2OH^- + H _2 \uparrow$
Note: In exothermic process, heat is released. When KOH is added to water, the temperature of resulting solution rapidly increases.

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

Calcium reacts __________ with water and forms calcium hydroxide and liberates hydrogen gas.

  1. vigroushly

  2. slowly

  3. violently

  4. uniformally
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Calcium reacts vigorously even with cold water and forms calcium hydroxide and liberates hydrogen gas.
$\displaystyle Ca+2H _2O \rightarrow Ca(OH) _2 + H _2 \uparrow$
Hence, the option (A) is the correct answer.

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

The solution of KOH is 

  1. acidic in nature.

  2. basic in nature.

  3. neutral in nature.

  4. alcoholic.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The solution of KOH is  basic in nature.
KOH is strong electrolyte and completely dissociates in aqueous solution to provide hydroxide ions. Due to this, aqueous KOH solution is strong alkali.
$\displaystyle KOH \rightarrow K^+ + OH^-$

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

Metals react with cold water and gives

  1. metal oxide

  2. metal oxide and oxygen

  3. metal oxide and hydrogen

  4. metal hydroxide and hydrogen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Metals react with cold water and gives metal hydroxide and hydrogen.
For example, sodium reacts with cold water and gives sodium hydroxide and hydrogen gas.
$\displaystyle 2Na + 2H _2O \rightarrow 2NaOH + H _2$

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

The piece of sodium melts in water at:

  1. $98^oC$
  2. $97.8^oC$
  3. $93^oC$
  4. $97^oC$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The piece of sodium melts in water at, $\displaystyle 97.8^oC$
Sodium reacts with cold water and gives sodium hydroxide and hydrogen gas.
$\displaystyle 2Na + 2H _2O \rightarrow 2NaOH + H _2$
The reaction is exothermic and releases the heat. The heat released melts Na. Then Na may disappear.  
The heat may burn hydrogen with an orange flame.