Chemistry Test - 8

Liquefied petroleum gas (LPG) mainly consists of propane and butane. Ethyl Mercaptan (CH₃CH₂SH) is an organic sulphur compound. It has a distinct smell that is used to detect the leakage of otherwise odourless LPG cooking gas.

We know,

n \(=\frac {Mass}{Molecular~weight}\) where \(n=\) No. of moles

For 1 mole of \(\mathrm{CaC}_{2}\)

\(\Delta \mathrm{H}=\Delta \mathrm{H}_{\mathrm{f}}(\mathrm{CaC})+\mathrm{H}_{\mathrm{f}}(\mathrm{CO})-\mathrm{H}_{\mathrm{f}}(\mathrm{CaO})\)

\(\Rightarrow -14.2-26.4+151.6=111.1 \mathrm{kcal}\)

\(\therefore\) For 100 moles, \(\Delta H=1.11 \times 10^{4}\) Kcal

The statement "atom is indivisible" was proposed byDalton.

John Dalton considered that "all matter is composed of small particle called the atom."

According to Dalton:

• Atom is the smallest indivisible part of matter which takes part in the chemical reaction.
• Atom is neither created nor be destroyed.

Characteristics of cathode rays are:

• The cathode rays start from the cathode and move towards the anode.
• These rays themselves are not visible but their behaviour can be observed with the help of phosphor materials such as ZnS.
• In the absence of an electrical or magnetic field, these rays travel in straight lines.
• In the presence of an electrical or magnetic field, the behaviour of cathode rays is similar to that expected from negatively charged particles, suggesting that the cathode rays consist of negatively charged particles, called electrons.
• The characteristics of cathode rays (electrons) do not depend upon the material of electrodes and the nature of the gas present in the cathode ray tube.

The element forms amphoteric oxide 'is true regarding the typical element belonging to the 1st group of p-block elements'.

• The element forms amphoteric oxide. For example, \(Al\) forms \(\mathrm{Al}_{2} \mathrm{O}_{3}\) which is amphoteric.
• The typical element belonging to the 1st group of \(p\)-block elements is \(\mathrm{Al}\). The group is group 13 or group III-A.
• The element forms a sulphate of formula \(\mathrm{M}_{2}\left(\mathrm{SO}_{4}\right)_{3}\).
• Thus, \(Al\) forms \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\). The element does not show variable valency. It is a metal.

Here \(\mathrm{CO}_{3}^{2-}\) and \(\mathrm{H}_{2} \mathrm{O}\) are Bronsted bases as water accept \(\mathrm{H}^{+}\) and \(\mathrm{CO}_{3}^{2-}\) is the conjugate base of \(\mathrm{HCO}_{3}^{-}\) and as the reaction is reversible so \(\mathrm{CO}_{3}^{2-}\) is accepting \(\mathrm{H}^{+}\).

\(\mathrm{HCO}_{3}^{-}+\mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{CO}_{3}^{2-}+\mathrm{H}_{3} \mathrm{O}^{+}\)

Ethane is an example of a saturated carbon compound.Saturated hydrocarbons are carbon compound that contains only single bonds between carbon atoms.Ethane is a colourless, odourless gas.Ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining.The chemical formula of Ethane is \(\mathrm{C}_{2} \mathrm{H}_{6}\).Ethane can be found underground in liquid form in rock formations.

Given that:

Atomic mass of \(N\) is \(14 \mathrm{u}\).

We know that, the molar mass is numerically equal to the atomic mass but expressed in g.

Therefore,

Mass of one mole of \(N=\) Molar mass \(=14 \mathrm{~g}\)

Then, mass of 3 moles of \(N=14 \times 3\)

\(=42 \mathrm{~g}\)

You should know that,
(1)$$ In a period, from left to right the acidic strength increases that mean basic nature decreases.
(2)$$ In a group, from top to bottom the basic nature increases that means acidic nature decreases.
Na, Mg, Al and K are present in periodic table like this : -

Classification means grouping of things.

The sorting of objects into groups with each group having its own characteristic properties, is called classification of objects.

All the objects having similar characteristics properties are placed in one group different groups and the objects having different properties are placed in different groups.