MCQ Questions for Class 8 Chemistry Materials Metals And Non Metals Quiz 6

Electric wires, coils, and machines are made of metals. Which of the following metal cannot be used for them?

0%
copper
0%
silver
0%
iron
0%
sodium

Select the objects from the following which have a characteristic shine known as lustre _____________.

0%
wooden bowls.
0%
towel and toys.
0%
shirts and scarfs.
0%
brass utensils.

The density of non metals is _____ when compared with metals.

0%
high
0%
same
0%
low
0%
none of the above

A metal

X

$X$ reacts with water to produce a highly combustible gas

Y

$Y$ , and a solution

Z

$Z$ . Another metal

P

$P$ reacts with

Z

$Z$ to give the same gas

Y

$Y$ .

X, Y, Z

$X,\ Y,\ Z$ and

P

$P$ respectively are:

0%
$Zn, H_2, Zn(OH)_2, Al$
0%
$Na, H_2,NaOH, Zn$
0%
$K, H_2, KOH, Al$
0%
$Li, H_2, LiOH, K$

Explanation

Sodium metal

(X)

$(X)$ reacts with water to produce a highly combustible gas hydrogen gas

(Y)

$(Y)$ and sodium hydroxide solution

(Z)

$(Z)$ .

2 N a (X) + 2 H_{2} O \to 2 N a O H + H_{2} (Y)

$2Na(X)\ +\ 2{ H }_{ 2 }O\ \rightarrow \ 2NaOH\ +\ { H }_{ 2 }(Y)$

On the other hand, zinc

(P)

$(P)$ reacts with sodium hydroxide solution

(Z)

$(Z)$ gives sodium zincate along with liberation of same hydrogen gas

(Y)

$(Y)$ .

2 N a O H (Z) + Z n (P) \to {N a}_{2} Z n O_{2} + H_{2} (Y)

$2NaOH(Z)\ +\ Zn(P)\ \rightarrow \ { Na }_{ 2 }Zn{ O }_{ 2 }\ +\ { H }_{ 2 }(Y)$

The Statue of Liberty is green because of

0%
green stone
0%
oxidized brass
0%
steel painted green
0%
oxidized copper

Metals are sonorous.

0%
True
0%
False

Consider the following statements

1

$1$ . Most of the metal oxides are insoluble in water.

2

$2$ . Sodium oxide and potasium oxide are metal oxides and hence insoluble in water.
The correct answer is?

0%
Only $1$ is true
0%
Only $2$ is true
0%
$1$ and $2$ both are true
0%
Neither of the two is true

The important metal used with iron to produce stainless steel is:

0%
Carbon
0%
Tin
0%
Chromium
0%
Aluminium

Metals generally reacts with dilute acids to produce a gas which burns with a 'pop' sound.

0%
True
0%
False

Explanation

Metals react with dilute acids to produce a gas which burns with a 'pop' sound.

Example:

Z n + 2 H C l \to Z n C l_{2} + H_{2} ↑

$Zn+2HCl\rightarrow ZnCl_2+H_2\uparrow$

Which one of the following statement, about glass is not correct ?

0%
Glass is often said to be a supercooled liquid.
0%
Glass has no definite melting point.
0%
Soda glass is harder than pyrex glass.
0%
Boron is present in pyrex glass.

Which of the following metals corrodes readily in moist air?

0%
Gold
0%
Silver
0%
Nickel
0%
Iron

Explanation

Iron metal corrodes readily in moist air. The reaction with moist air is as follows:

F e + O_{2} + H_{2} O / H^{+} \to F e_{2} O_{3} . x H_{2} O Rust

$Fe +O_2+H_2O/H^{+} \rightarrow \underset{\text{Rust}}{Fe_2O_3 .xH_2O}$

Which of the following element does not occur in liquid state?

0%
$Hg$
0%
$Li$
0%
$Ga$
0%
$Cs$

When metallic copper comes in contact with moisture, a green powdery/pasty coating can be seen over it. This is chemically known as

0%
Copper sulphide - Copper carbonate
0%
Copper carbonate - Copper sulphate
0%
Copper carbonate - Copper hydroxide
0%
Copper Sulphate - Copper sulphide

Explanation

When metallic copper comes in contact with moisture, a green powdery/ pasty coating can be seen over it. This is chemically known as basic copper carbonate or copper carbonate - copper hydroxide.

C u + O_{2} + C O_{2} + H_{2} O \to C u (O H)_{2} . C u C O_{3}

$Cu +O_2 +CO_2 +H_2O \rightarrow Cu(OH)_2. CuCO_3$

Non-metals are lustrous and good conductors of heat and electricity.

0%
True
0%
False

Explanation

False

$\text{False}$

Generally, metals are lustrous and are good conductors of heat and electricity.

Non-metals are generally non-lustrous and poor conductors of heat and electricity. Hence the given statement is false.

Which of the following is not a metal?

0%
copper
0%
aluminium
0%
sulphur
0%
iron

Amit has learned that non-metals on beating with a hammer are generally broken into pieces. Which of the following is a non-metal?

0%
iron nail
0%
copper plate
0%
aluminium wire
0%
piece of coal

The substance that will be flattened on beating with a hammer is:

0%
crystal of iodine
0%
piece of coal
0%
lump of sulphur
0%
zinc granule

Metals generally react with dilute acids to produce hydrogen gas . Which one of the following metals does not react with dilute hydrochloric acid?

0%
magnesium
0%
iron
0%
aluminium
0%
copper

Generally, metals are solid. Which one of the following metals is found in a liquid state at room temperature?

0%
$Na$
0%
$Fe$
0%
$Cr$
0%
$Hg$

Explanation

Hint: There are some exceptions in the properties of metals like they exist in the liquid state at room temperature.

Step 1: Generally, metals have high melting and boiling point due to strong metallic bonding. Metals mostly exist in solid state at room temperature because of the high melting point. Metals like sodium, iron, chromium, etc. exist in the solid state at room temperature.

Step 2: Mercury is a metal that exists in the liquid state at room temperature. It is because of the weaker metallic bond compared to other metals that mercury exists in the liquid state. The electrons in the mercury metal are tightly bonded by the nucleus so the metallic bond is weak.

Final step: So, the correct option is (D) $Hg.$

Oxides of non-metals are acidic in nature. True or False

0%
True
0%
False

True or False:

Articles made of metals produce a ringing sound when struck hard.

0%
True
0%
False

A less reactive metal replaces a more reactive metal from its salt solution. True or False?

0%
True
0%
False

An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following

0%
Mg
0%
Na
0%
P
0%
Ca

Explanation

Hint: Generally alkali metals are soft and can be cut with a knife and are highly reactive.

Step 1: Alkali metals like sodium, potassium, etc are soft and can be easily cut with a knife. They are highly reactive metals and undergo combustion when exposed to air. These metals react vigorously even with cold water. So, they are stored in kerosene oil.

Step 2:

A. Magnesium (Mg) is a soft metal that can be cut with a knife but it does not react significantly with cold water.

B. Sodium (Na) is a soft alkali metal that can be cut with a knife and reacts vigorously with cold water.

C. Phosphorous (P) is a non-metal and its allotropes can be cut with a knife and reacts with water at high temperature in steam form.

D. Calcium (Ca) is a soft metal that can be cut with a knife but not as easily as sodium. Even it does not react so vigorously with cold water and is not so reactive like sodium in air.

Step 3: Sodium is a soft metal and highly reactive because of the loosely bonded single valence electrons. The reaction of sodium with air and water are as follows:

4 N a (s) + O_{2} (g) \to 2 N a_{2} O (s)

$4Na(s)+O_2(g)\to 2Na_2O(s)$ ----- with air

2 N a (s) + H_{2} O (l) \to 2 N a O H (a q) + H_{2} (g)

$2Na(s)+H_2O(l)\to 2NaOH(aq)+H_2(g)$ ---- with water

Final step: So, the correct option is (B) Na.

Which among the following statements are incorrect for magnesium metal?

0%
It burns in oxygen with a dazzling white flame
0%
It reacts with cold water to form magnesium oxide and evolves hydrogen gas
0%
It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas
0%
It reacts with steam to form magnesium hydroxide and evolves hydrogen gas

Explanation

Hint: Magnesium reacts with hot water and steam, but not with cold water.

Step 1: Magnesium is a reactive metal but less reactive compared to sodium, potassium, calcium, etc. It is because two electrons valence is strongly held to the nucleus compared to sodium, potassium, or calcium.

Step 2: When magnesium ribbon burns in the presence of oxygen, it burns with a dazzling white flame. Before burning, the magnesium ribbon is rubbed with sandpaper to remove the oxide layer at the surface of the magnesium ribbon.

Step 3: Magnesium metal does not show any significant reaction with cold water but reacts with hot water to give the slightly soluble magnesium hydroxide and reacts with steam to produce white magnesium oxide and hydrogen gas. The reactions are as follows:

a . M g (s) + H_{2} O (c o l d) \to M g (O H)_{2} (s) + H_{2} (g) - - - - - Negligible Reaction

$a. Mg(s)+\underset{(cold)}{H_2O}\to Mg(OH)_2(s)+H_2(g) -----\text{Negligible Reaction}$

b . M g (s) + H_{2} O (h o t) \to M g (O H)_{2} (s) + H_{2} (g)

$b. Mg(s)+\underset{(hot)}{H_2O}\to Mg(OH)_2(s)+H_2(g)$

c . M g (s) + H_{2} O (s t e a m) \to M g O (s) + H_{2} (g)

$c. Mg(s)+\underset{(steam)}{H_2O}\to MgO(s)+H_2(g)$

Final step: So, the correct options are -
B. It reacts with cold water to form magnesium oxide and evolves hydrogen gas.
D. It reacts with steam to form magnesium hydroxide and evolves hydrogen gas.

Based on the physical properties of metals, indicate whether the following statement is true or false :

Copper metal is sonorous.

0%
True
0%
False

What is formed by reaction of non-metal oxide with water?

0%
Acid
0%
Base
0%
Salt
0%
Metal

Explanation

An acid is formed by reaction of non-metallic oxide with water.

Example:

S O_{3} (g) Non-metallic oxide + H_{2} O (l) Water \to H_{2} S O_{4} (a q) Acid

$\underset{\text{Non-metallic oxide}}{SO_{3} (g)} + \underset{\text{Water}}{H_{2}O (l)}\rightarrow \underset{\text{Acid}}{H_{2}SO_{4} (aq)}$

Which gas is produced by reaction of base with metal?

0%
Carbon dioxide
0%
Dioxygen
0%
Dihydrogen
0%
Dinitrogen

Based on the physical properties of metals, indicate whether the following statement is true or false :

The ductility of tungsten is high.

0%
True
0%
False

When sodium hydroxide reacts with aluminium metal:

0%
sodium aluminate and water gas are formed
0%
sodium aluminate and hydrogen gas are formed.
0%
no reaction
0%
can't say

Explanation

Sodium aluminate and hydrogen gas are formed when sodium hydroxide reacts with aluminium metal.

$2NaOH +2Al +2H_2O \rightarrow 2NaAlO_2 +2H_2$

Option B is correct.

A non-metal which is lustrous is :

0%
brass
0%
graphite
0%
silicon
0%
nitrogen

CBSE Questions for Class 8 Chemistry Materials Metals And Non Metals Quiz 6 - MCQExams.com

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Practice Class 8 Chemistry Quiz Questions and Answers

CBSE Questions for Class 8 Chemistry Materials Metals And Non Metals Quiz 6 - MCQExams.com

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Practice Class 8 Chemistry Quiz Questions and Answers

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