Tag: metals

Quizzes (9) Questions (306)

Questions Related to metals

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.

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

$Na+H _2O\rightarrow NaOH+H _2$ 


Balance the following reaction.

  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. $Na+\dfrac12 H _2O\rightarrow NaOH+H _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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

When potassium is added to water, it burns with :

  1. pink flame

  2. blue flame

  3. red flame

  4. lilac flame
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  1. pink

  2. orange

  3. yellow

  4. purple
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $B$.

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

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

  1. $Cu, CuO$
  2. $Pb, PbO$
  3. $Fe, Fe _2O _3$
  4. $Cr, Cr _2O _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

What is characteristics of solution when potassium reacts with water?

  1. Colourless basic solution

  2. Orange coloured basic solution

  3. Yellowish basic solution

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
$2K + 2H _2O \rightarrow 2KOH + H _2$

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

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

  1. Na

  2. Ca

  3. Mg

  4. Fe
Reveal answer Fill a bubble to check yourself
D Correct answer
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