Tag: chemistry

Questions Related to chemistry

Natural water is:

chemistry environment environmental impact: global warming green house effect geobiochemical cycle

  1. spring water

  2. river water

  3. rain water

  4. well water

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Correct Option: A,B,C,D
Explanation:
Natural water is defined as the water that is:
1. obtained directly from underground sources
2. has natural origin from evaporation and condensation of sea water
or melting of glaciers.
This includes all natural sources of water such as river, lakes, spring, rain, well water.
option A,B,C,D are correct.

State whether true or false :

All the elements having one electron in their outermost shell are metals.

chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

  1. True

  2. False

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Correct Option: B
Explanation:

Hydrogen has one electron in its outermost shell with electronic configuration of $1s^1$ but it is a non-metal. therefore all elements having one electron in their outermost shell are not metals. Hydrogen is an exception.


 Therefore, option B is correct.

The most abundant metal in the earth's crust is :

chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

  1. Oxygen

  2. Aluminium

  3. Calcium

  4. Gold

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Correct Option: B
Explanation:

Percent abundance of given elements in the earth's crust are :


Oxygen - 46.6%
Aluminium - 8.1%
calcium-3.63%
gold-0.0011%

But oxygen is a non-metal and aluminium, calcium and gold are metals. 

Therefore, Aluminium is the most abundant metal in the earth's crust.

Therefore, option B is correct.

Elements are classified into four major categories:

chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

  1. Metals.

  2. non-metals.

  3. Metalloids.

  4. Noble Gases.

  5. All of the above.

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Correct Option: E
Explanation:

Elements are classified into four major categories: Metals, non-metals, Metalloids, and noble gases

The second most abundant metal present in the crust of the earth is :

chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

  1. $Ca$

  2. $Al$

  3. $Cu$

  4. $Fe$

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Correct Option: D
Explanation:

Iron is the second most abundant metal in the earths crust. It is found in the molten form inside the crust of the earth. In the presence of air and moisture it forms its oxide but the alloy of steel is widely used as pipes,it is unreactive in nature.

________ are elements which can accept one or more electrons and form negative ions.

chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

  1. Metals

  2. Non-metals

  3. Metalloids

  4. None of these

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Correct Option: B
Explanation:

Non-metals are elements which can accept one or more electrons and form negative ions.

In a closed system :

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. energy is not exchanged

  2. matter is exchanged

  3. energy is only exchanged

  4. energy and matter are exchanged

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Correct Option: C
Explanation:

In a closed system Matter is not exchanged but Energy is exchanged.

So option c is correct

Which of the following is a state function ?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $q\times w$

  2. $q+w$

  3. $\dfrac{q^2}{w^2}$

  4. $\sqrt{qw}$

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Correct Option: B
Explanation:

Solution:- (B) $q + w$

From first law of thermodynamics,
$\Delta{U} = q + w$
As we know that $\Delta{U}$ is a state function, thus we can say that $q + w$ is a state function.

The following two equilibria exist simultaneously in a closed vessel :
$PCI _5(g) \rightleftharpoons PCI _3(g) + Cl _2(g)$
$COCI _2(g) \rightleftharpoons CO (g) + CI _2 (g)$
If some CO is added into the vessel, then after the equlibrium is attained again, concertration of ?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $PCI _5$ will increase

  2. $PCI _5$ will decrease

  3. $PCI _5$ will remain unaffected

  4. $CI _2$ will increase

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Correct Option: C
Explanation:

Given reactions are,

$PCl _5 \rightleftharpoons PCl _3+Cl _2$
$COCl _2\rightleftharpoons CO _{(g)}+Cl _2$
If some $CO$ is added into the vessel, the concentration of $PCl _5$ will remain unaffected, because $CO$ reacts with $Cl _2$ and forms $COCl _2$, not going to effect the concentration of $PCl _5$ .

Bond dissociation enthalphies of ${ H } _{ 2 }\left( g \right) $ and ${ N } _{ 2\left( g \right)  }$ are enthalpy of formation of $N{ H } _{ 3 }\left( g \right) $ is $-46 kJ mol^{-1}$. What is enthalpy of atomization of $N{ H } _{ 3 }\left( g \right) $?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $390.3 kJ mol^{-1}$

  2. $1170.9kJ mol^{-1}$

  3. $590 kJ mol^{-1}$

  4. $720 kJ mol^{-1}$

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Correct Option: B