Chemistry M.C.Q (1 Marks)

On moving down the group size of the central atom increases i.e. bond length increases and bond dissociation enthalpy decreases.

Weak dispersion forces are present between particles of noble gases. Ionization enthalpy of molecular oxygen is very close to that of xenon.

Black phosphorus is the most thermodynamically stable allotropic form of phosphorus.

The colour and state of phosphorus pentoxide is white crystalline solid.

The word Argon represents the term Lazy.

Helium is the least polarizable noble gas due to presence of weakest Van der Waal's forces.

He gets heated at their inversion temperature on expansion into vacuum.

In clathrate bond is not formed. There is only dipole- induced dipole interaction which is not a bond.

Several catalysts are being utilized. The catalyst is iron containing iron oxide, magnesium oxide, aluminium oxide and ruthenium on carbon.

Tetra atomic elements are those which are made up of four atoms.
A common and biologically important element that consists as molecules of four atoms chemically bonded together is the element phosphorus.

At low temperatures nitrogen can be liquefied on compression.

In the preparation of ammonia gas from ammonium chloride and calcium hydroxide, the reactants are ground thoroughly to provide a maximum surface area of the reactants which helps in speeding up the reaction.

Argon is lazy gas because during his experiments to remove all gases from air, Sir William Ramsay kept getting the same proportion of an inert gas left behind. He did a lot of experiments to make this gas react with most reactive substance like fluorine, potassium etc. but it did not react with anything. He named this gas argon from a Greek word 'Argos' which means lazy or inert or inactive.

Helium has abnormal behavior in its liquid state due to its small size and nearly ideal behavior.

Due to small size of helium, it can not be absorbed over activated coconut charcoal.

Anaerobic bacteria works in the absence of oxygen.
Example is yeast.

White phosphorous is very reactive therefore it is stored under water.

Fluorine, chlorine, bromine, and iodine form a family of the related elements called “halogens” because they give salts when they react with metals.

Oxygen is diatomic gas.
Phosphorous is tetra atomic.
Sulphur is polyatomic.
Whereas being an inert gas, Krypton is monoatomic.

Each face of the tetrahedron are equilateral.

Fluorine is the most electronegative element so it cannot show positive oxidation state.

Ammonia is less dense than air so it is collected by upward delivery or gas syringe method.
In upward delivery method a gas jar is connected by a tube to flask that is giving off gas.
The gas that is less dense than air rises to the top of gas jar.
The air in the gas jar is displaced until the gas jar is filled with collected gas.
Ammonia is very soluble gas so the collection apparatus should be dry and not collected over water.

All the noble gases are colourless and odourless gases, in addition to being chemically inert and stable.

Astatine belongs to halogen family.

Nitrates are less abundant than phosphates in the earth's crust because they are soluble in water. Moreover they can also be reduced by numerous microbes present in earth's crust.

Structure of Cyclotrimetaphosphoric acid.

In a period the last element will have completely filled configuration by filling up that orbital completely. Hence they are called noble gases or inert elements as they do not participate in the bonding formation. They are also called zero group elements as they have zero electron affinity that is zero tendency in accepting electrons as they already have stability.

The name "argon" is derived from the Greek word , meaning "lazy" or "inactive", as a reference to the fact that the element undergoes almost no chemical reactions.

Finely divided iron is used as catalyst in the manufacture of ammonia by Haber's process.

Atomic weight of hydrogen is least so it is the lightest gas.
Hydrogen dirigibles are able to float in the atmosphere.

Higher the standard reduction potential higher will be the oxidizing power.