Chemistry of Gases and Applications

As established in previous questions, the primitive atmosphere was reducing and lacked free oxygen, which only became abundant after the evolution of photosynthetic organisms.

Dissociation in chemistry and biochemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into smaller particles such as atoms, ions or radicals, usually in a reversible manner. It may or may not form charged species as shown below. 

i). $NaCl \leftrightharpoons Na^++Cl^-$

ii). $N _2O _4 \leftrightharpoons 2NO _2$

• The Miller-Urey experiment was an experiment that simulated hypothetical conditions present on the early Earth in order to test what kind of environment would be needed to allow life to begin. The experiment is considered to be the classic experiment on the origin of life. 
• It was conducted in 1953 by Stanley L. Miller and Harold C. Urey at the University of Chicago. The experiment used water (H2O), methane (CH4), ammonia (NH3) and hydrogen (H2) - materials which were believed to represent the major components of the early Earth's atmosphere. The chemicals were all sealed and circulated inside a sterile array of glass tubes and flasks connected together in a loop, with one flask half-full of liquid water and another flask containing a pair of electrodes. 
• The liquid water was heated to add water vapor to the chemical mixture and the resulting gases were circulated around the apparatus, simulating the Earth's atmosphere. The flask with heated water represents water on the Earth's surface and the recycled water vapor is just as water evaporates from lakes and seas, before going into the atmosphere and forming into the rain. Sparks were fired between the electrodes to simulate lightning storms (believed to be common on the early earth) through the water vapors, and then the vapors were cooled again so that the water could condense (simulating the oceans) and trickle back into the first water flask in a continuous cycle. 
• At the end of one week of continuous operation, Miller and Urey observed, by analyzing the cooled water, that as much as 10-15% of the carbon within the system was now in the form of organic compounds. Two percent of the carbon had formed amino acids, including 13 of the 22 that are used to make proteins in living cells, with glycine as the most abundant. 

A- The Miller-Urey experiment or Miller experiment was an experiment that instigated the condition which were thought to be present in early earth or primitive earth. Hecreated electric discharge in a closed flask containing a mixture of ammonia(NH3), methane(CH4), hydrogen(H2) and water vapour(H2O) at 800 degree celcius and observed formation of amino acids The ratio of CH4,NH3 and H2 was 2:1:2.

The primitive atmosphere of earth was reducing atmosphere with no oxygen but was rich in water vapour, carbon monoxide, carbon dioxide, nitrogen and hydrogen. Owing to immense long lasting rainstorms, a tremendous amount of lightening was generated. Lightening provided energy for chemical reactions between hydrogen and nitrogen and carbon to form ammonia and methane. So, the correct answer is option A.  

Modern synthetic detergents are alkyl or aryl sulphonates produced from petroleum (or coal) and sulphuric acid. They can be defined as the sodium or potassium salt of a long chain alkyl benzene sulphonic acid or the sodium or potassium salt of a long chain alkyl hydrogen sulphate, that has cleansing properties in water.
They are used in washing powders in a proportion of about $15-30\%$.

Chlorine is gas, bromine is liquid and iodine is solid.

Chlorine is a greenish-yellow gas. As we go down the group, the colour of halogens gets darker. Fluorine is pale-yellow in colour, chlorine is greenish-yellow. Bromine is red-brown and iodine is purple.

The statement which is not true about air is that it has a chemical formula. Air has no chemical formula. It is a mixture of gases.

Oxygen is required for burning or combustion to take place. 

Switching from air to pure oxygen eliminates NO production and also saves fuels by more efficient burning, thus, having less wastage. Hence, this is an application of Green chemistry.

Alkaline hydrogen peroxide is used as a strong bleaching agent due to the oxidation state of $-1$ in the compound.

The first three compounds are chlorofluoro carbons which are harmful to ozone and unfriendly to the environment. These are used in refrigerators. so a compound called $CF _3CH _2F$ was discovered, which is friendly to the environment and used in refrigerators.

In a flame of pure hydrogen gas, burning in air, the hydrogen (H$ _2$) reacts with oxygen (O$ _2$) to form water (H$ _2$O) and releases energy. If carried out in atmospheric air instead of pure oxygen, as is usually the case, hydrogen combustion may yield small amounts of nitrogen oxides, along with the water vapour.

NITROGEN is used as a refrigerant. Nitrogen is a liquid at temperatures below 196.5 C and is used as a refrigerant for such things as preservation of blood and cooling of large computer systems, as well as some industrial uses. Being a liquid, it is more convenient to use for low temperature cooling than dry ice. Liquid nitrogen is also used in oil wells to build up pressure in order to force crude oil upward.