Tag: chemistry

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

Natural water is:

  1. spring water

  2. river water

  3. rain water

  4. well water
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
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.
Multiple choice chemistry metals and non metals introduction to non-metals occurence of metals occurrence of metals and non metals

State whether true or false :

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. Oxygen

  2. Aluminium

  3. Calcium

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

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

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

  1. $Ca$
  2. $Al$
  3. $Cu$
  4. $Fe$
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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 ?

  1. $PCI _5$ will increase
  2. $PCI _5$ will decrease
  3. $PCI _5$ will remain unaffected
  4. $CI _2$ will increase
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $PCl _5$ .

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

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) $?

  1. $390.3 kJ mol^{-1}$
  2. $1170.9kJ mol^{-1}$
  3. $590 kJ mol^{-1}$
  4. $720 kJ mol^{-1}$
Reveal answer Fill a bubble to check yourself
B Correct answer