Tag: physics

The dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates so dew point is a temperature at which the air becomes saturated.

A fan produces a feeling of comfort because of evaporation of sweat. As evaporation releases heat energy, and evaporation of sweat. Results in feeling cool in those body parts.

The force of attraction between the molecules of matter is called the intermolecular force of attraction.

$v _{rms}\propto \sqrt{T}$
$\Rightarrow \displaystyle\frac{v^2 _1}{v^2 _2}=\frac{T _1}{T _2}$
$\Rightarrow \displaystyle\frac{v^2}{4v^2}=\frac{273}{T _2}$
$\Rightarrow \displaystyle T _2=1092K$
$=819^oC$

Answer is C.

When a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants. 
The types of cells mentioned in option A and option are correct.
Hence, option C is correct.

When dissolved in fluid, salts tend to break apart into their component ions, creating an electrically-conductive solution. Common salt is one such salt. common salt is  $ NaCl$ which gives $Na^+$ and $Cl^-$.

Ammonium chloride, as a paste, is the electrolyte in a dry cell. Hence the above statement is false.

the Daniel cell is a type of electrochemical cell invented in 1836. it is consisted of a copper pot filled with a copper sulfate solution , in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. Daniel cell is also called Zn-Cu cell and has constant e.m.f of 1.08 volts.