Tag: reaction of metals

Questions Related to reaction of metals

The piece of sodium melts in water at:

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. $98^oC$

  2. $97.8^oC$

  3. $93^oC$

  4. $97^oC$

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Correct Option: B
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.

$Na+H _2O\rightarrow NaOH+H _2$ 


Balance the following reaction.

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. $2Na+2H _2O\rightarrow 2NaOH+H _2$

  2. $Na+H _2O\rightarrow NaOH+2H _2$

  3. $2Na+H _2O\rightarrow NaOH+H _2$

  4. $Na+\dfrac12 H _2O\rightarrow NaOH+H _2$

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Correct Option: A
Explanation:

Sodium reacts with cold water and gives sodium hydroxide and hydrogen gas. The balanced chemical equation is

$\displaystyle 2Na + 2H _2O \rightarrow 2NaOH + H _2$

When potassium is added to water, it burns with :

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. pink flame

  2. blue flame

  3. red flame

  4. lilac flame

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Correct Option: D
Explanation:

When potassium is added to water, it burns with a lilac flame.


Potassium reacts with cold water and gives potassium hydroxide and hydrogen gas.

$\displaystyle 2K + 2H _2O \rightarrow 2KOH + H _2$

The reaction is so vigorous that the evolved hydrogen catches fire spontaneously.

Hence the correct option is D.

The colour of flame produced when a chunk of sodium comes in contact with water is :

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. pink

  2. orange

  3. yellow

  4. purple

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Correct Option: B
Explanation:

The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic. 


During the reaction, the sodium metal may well become so hot that it catches fire and burns with a characteristic orange colour.

Hence, the correct option is $B$.

A reddish brown colored element $X$ on heating in air, becomes a black colored compound $Y$.  The compound $X$ and $Y$ are :

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. $Cu, CuO$

  2. $Pb, PbO$

  3. $Fe, Fe _2O _3$ 

  4. $Cr, Cr _2O _3$

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Correct Option: A
Explanation:

$X$ is copper $(Cu)$ and the black-coloured compound formed is copper oxide $(CuO)$. The equation of the reaction involved on heating copper in given below.

$2Cu + O _{2} \rightarrow 2CuO$.
All other elements that are given are not black in colour

$Pb$ is grey in colour.
$Fe$ is silver-grey.
$Cr$ is steely-grey.

What is characteristics of solution when potassium reacts with water?

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. Colourless basic solution

  2. Orange coloured basic solution

  3. Yellowish basic solution

  4. None of these

Show answer
Correct Option: A
Explanation:

When potassium reacts with water, a colourless basic solution is obtained.
 When potassium is added to water potassium hydroxide (a strong base) and hydrogen gas are obtained. The reaction of potassium with water is exothermic.
$2K + 2H _2O \rightarrow 2KOH + H _2$

Which one of the following metals do not react with cold as well as hot water?

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. Na

  2. Ca

  3. Mg

  4. Fe

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Correct Option: D
Explanation:

The metal sodium, calcium and magnesium are highly reactive to water and make their hydroxides. 
Iron is a less reactive metal and does not show any reaction while treated with cold as well as hot water but will react with steam and form metal oxides and hydrogen gas.
$3Fe(s) +4H _2O(g) \rightarrow Fe _3O _4(s)+4H _2(g)$
  Iron         Steam          Iron(III) oxide   Hydrogen

Which of the following mixture on mixing with distilled water will make the water hard?

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. $Na _2SO _4+NaCl$

  2. $NaNO _3+NH _4NO _3$

  3. $MgSO _4+Na _2SO _4$

  4. $KCl+NaCl$

Show answer
Correct Option: C
Explanation:

Hard water is due to presence of $C{a^{2 + }}$ and $M{g^{2 + }}$.

So, option C is appropriate.

An alkali metal $A$ gives a compound $B$ (molecular mass $=40$) on reacting with water. The compound $B$ gives a soluble compound $C$ on treatment with aluminium oxide. Metal $A$ is:

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. $Al$

  2. $K$

  3. $Na$

  4. $Mg$

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Correct Option: C
Explanation:

Alkali metal $(A)$ is sodium ($Na$) which forms $NaOH$ (compound $B$) with water .The reaction can be written as:
$2Na + 2H _{2}O \rightarrow  2NaOH + H _{2}$
$NaOH$ reacts with aluminium oxide($ Al _{2}O _{3}$) to form sodium aluminate (compound $C$) with chemical formula $NaAlO _{2}$.The reaction can be written as:
$Al _{2}O _{3} + 2NaOH \rightarrow  2NaAlO _{2} + H _{2}O$

Which of the following elements produces basic oxide on reacting with oxygen?

chemistry metals reaction of metals reactions of metals chemical properties of metals

  1. Chorium

  2. Sulphur

  3. Sodium

  4. Magnesium

Show answer
Correct Option: C,D
Explanation:

Sodium and magnesium metal reacts with the oxygen of the air at room temperature to form sodium oxide and magnesium oxide respectively. These oxides react with water to form hydroxides.
$4Na + O _2 \rightarrow 2Na _2O$
$Na _2O + H _2O \rightarrow 2NaOH$
$2Mg + O _2 \rightarrow 2MgO$
$MgO + H _2O \rightarrow Mg(OH) _2$