Tag: chemistry

Questions Related to chemistry

$2K(s) + 2H2O(l) \rightarrow$


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

  1. $2KOH(aq) + H _2(g) +$ heat energy

  2. $2KOH(aq) + H _2(g)$

  3. $2KOH(aq) + H _2O(g) +$ heat energy

  4. No reaction

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Correct Option: A
Explanation:

$2K(s) + 2H _2O(l) \rightarrow $2$KOH$(aq) + $H _2(g)$ + heat energy

The gaseous product formed when magnesium reacts with boiling water is :

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

  1. hydrogen

  2. washing soda

  3. sulphurous

  4. calcium oxide

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Correct Option: A
Explanation:

Hydrogen gas is formed when magnesium reacts with water to form its hydroxide as Mg is highly reactive with water and acids. It is present on the top of the activity series. So, it is a very reactive metal.

Aluminium reacts with oxygen to form ______ .

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

  1. $AlO$

  2. $AlO _2$

  3. $Al _2O _3$

  4. None of the above

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Correct Option: C
Explanation:

$4Al(s) + 3O _2(g) \rightarrow 2Al _2O _3(s)$

Which of the following compounds can be reduced to copper when heated with coke?

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

  1. Copper sulphate

  2. Copper oxide

  3. Hydrogen chloride

  4. Ammonia

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Correct Option: B
Explanation:

The metals, which are low in the reactive series, undergo reduction reaction. Their metal oxides react with carbon to reduce the metal oxide to its metal and form an oxide of carbon.
$2CuO+C \rightarrow 2Cu+CO _2$

 Name a metal which reacts with steam?

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

  1. Sodium

  2. Potassium

  3. Lithium

  4. Magnesium

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Correct Option: D
Explanation:

Metals from magnesium to iron in the activity series of metals, react with steam (but not $H _2O$) to form the metal oxide and hydrogen gas.

$\text{Magnesium + steam} \to \text{Magnesium oxide + Hydrogen}$
$Mg + H _2O \to MgO + H _2\uparrow$

Pertaining to metallurgy, when "M" is a metal, its oxide MO is :

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

  1. acidic

  2. basic

  3. neutral

  4. none of these

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Correct Option: B
Explanation:

Metal forms basic oxides which reacts with water and forms base as
$M-2e^- \rightarrow M^{+2}$
$MO+H _2O \rightarrow M(OH) _2$

Name the following: A metal which does not react with cold water but reacts with steam.

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

  1. Magnesium

  2. Iron

  3. Zinc

  4. All of these

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Correct Option: D
Explanation:

Magnesium has almost no reaction with cold water. It reacts very slowly with hot water.  It reacts with steam when being heated and gives hydrogen gas and metal oxide.
Magnesium + Water $\rightarrow$  Magnesium hydroxide + Hydrogen gas
Zinc and iron do not react with cold or hot water.  They react with  steam slowly to give the respective oxides:
Zinc + Steam $\rightarrow$  Zinc oxide  + Hydrogen gas
Iron + Steam $\rightarrow$ Iron(II) iron(III) oxide  + Hydrogen gas

On reaction with water, an active metal produces:

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

  1. oxygen

  2. nitric acid

  3. base

  4. metal hydroxide

  5. none of the above

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Correct Option: D
Explanation:

The reactivity of active metals can be demonstrated by dropping pieces of $Li, Na, K$ into water. $Li$ reacts slowly with water, $Na$ reacts more rapidly and $K$ reacts violently. For a reaction between sodium and water, it can be divided into two halves. One-half reaction describes what happens when sodium atoms lose electrons. The other half describes what happens when water molecules gain these electrons. An overall equation is obtained for the reaction which shows the formation of metal hydroxide and evolution of hydrogen gas.
$2Na\left( s \right) +2{ H } _{ 2 }O\left( l \right) \rightarrow 2{ Na }^{ + }\left( aq \right) +2{ OH }^{ - }\left( aq \right) +{ H } _{ 2 }\left( g \right) \uparrow $

Metals combine with oxygen to produce:

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

  1. neutral acid

  2. basic oxide

  3. acidic acid

  4. amphoteric oxide

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Correct Option: B
Explanation:
An oxide that combines with water to give an acid is termed as an acidic oxide. The oxide that gives a base in water is known as a basic oxide.
Generally Group 1 and Group 2 metals  form bases called base anhydrides or basic oxides e.g.,
$4K+O _2 \rightarrow 2K _2O$
Basic oxides are the oxides of metals. If soluble in water, they react with water to produce hydroxides (alkalies) e.g.,
$K _2O(s)+H _2O(l) \rightarrow 2KOH(aq)$)

Name one metal that will not react with cold water but will react with steam.

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

  1. Zinc

  2. Iron

  3. Calcium

  4. Magnesium

Show answer
Correct Option: A
Explanation:

Zinc is a metal which doesnot react with cold water but reacts with steam. The chemical equation for the reaction can be written as:
$ Zn + H _{2}O \rightarrow ZnO + H _{2}$
         (steam)