Free Practice Questions for Chemistry in General-studies

Option 3 is correct.

Important Points:

• The strength of acids and bases depends on the number of H⁺ ions and OH^- ions produced, respectively. 
• Acids which give more H⁺ ions are called strong acids and acids which give less H⁺ ions are called weak acids. 
• Similarly, bases which give more OH^- ions are called strong bases and bases which give less OH^- ions are called weak bases.

Acetic acid is an organic acid.

Important Points:

• Acids that have an natural origin (plant or animal) are known as organic acid. 
• Acetic acid, CH₃COOH is a weak organic acid. 
• It is also known as ethanoic acid. 
• It belongs to a group of acids called carboxylic acids.
• 5-8% solution of acetic acid in water is called vinegar and is used widely as a preservative in pickles. 

Natural sources of some organic acids are:-

Mineral Acid -

• The acids that are obtained from minerals are called inorganic acids or mineral acids.
• They usually have non-metallic elements in their structure like chlorine, sulphur, nitrogen and phosphorus.

Examples : Carbonic acid H₂CO₃ , Hydrochloric acid HCl , Phosphoric acid H₃PO₄ , Perchloric acid HClO₄ , Nitric acid HNO₃ & Sulphuric acid H₂SO₄.

The element with the Latin name Plumbum is lead.

Important points:

• Lead is a transition element with atomic number 82.
• It is used in making alloys, lead accumulators, and lead chambers, etc. 
• It is used in covering of electric cables. Lead oxide is amphoteric oxide.
• It is used in rubber industry and storage batteries. 
• Lead carbonate is also known as white lead.  
• Tetraethyl lead is used as an anti knocking agent in petrols.

Caesium .

Important Points :

• Caesium (Cs) is a soft alkali metal. It is used in photoelectric cells.
•  Caesium has very low melting points. 
• This metal will melt if kept on the palm.
• It is used in atomic clocks.

Option Explanation :  

Thorium :

• Atomic number - 90
• It is a radioactive element. 
• It occurs naturally and abundantly in the ore of monazite near sea coast.
• It is mainly extracted from monazite ore.
• Thorium is used as a tungsten filament of arc lamps, as an X-ray target, as a glow tube electrode, in the production of nuclear power.

Uranium :

• All minerals of uranium are radioactive.
• It is also called metal of hope.
• Uranium oxide is known as yellow cake.

Polonium :

• French physicists Marie and Pierre Curie discovered polonium.
• Polonium is unstable, so it easily disintegrates into other elements. so, it has no stable isotopes on Earth.
• Tobacco contains low amounts of polonium.

Calcium carbonate is used in the manufacture of quick lime.

Important Points-

• Calcium carbonate is a white friable powder. It is almost insoluble in water. 
• When calcium carbonate is heated to 1200 K, it decomposes to release carbon dioxide and form calcium oxide (quick lime). 
• It is used as a building material in the form of marble. 
• Calcium carbonate, along with magnesium carbonate, is used as a flux in the extraction of metals such as iron. 
• It is also used as an antacid, mild abrasive in tooth paste.

 When carbon dioxide is passed through lime water it turns milky due to the formation of calcium carbonate. 

Important Points:

• On passing excess of carbon dioxide, the precipitate dissolves to form calcium hydrogen carbonate. 
• Calcium carbonate occurs in nature in several forms like limestone, chalk, marble etc.
• It is also used as an antacid.

Washing soda (sodium carbonate) is used in the manufacture of glass, soap, borax and caustic soda.

Important Points:

• Washing soda is a white, crystalline compound that is soluble in water.
• It is made by the reaction of sodium hydroxide (caustic soda) with carbon dioxide.
• Washing soda is used in a variety of industries, including glassmaking, soapmaking, and textile manufacturing.
• It is also used as a cleaning agent and a water softener.

The colour of pure ozone is Pale blue.

Important Points:

• Ozone is an allotropic form of oxygen. 
• Ozone layer protects the earth’s surface from an excessive concentration of ultraviolet (UV) radiations.
• Pure ozone is a pale blue gas, violet-black solid and dark blue liquid.

Chlorine water on standing loses its yellow colour due to the formation of HCl and HOCl. 

Important Points:

• Chlorine is a greenish –yellow colour gas. 
• It has pungent and suffocating odour. 

Uses of chlorine :

• It is used for bleaching woodpulp (required for the manufacture of paper and rayon), bleaching cotton and textiles.
• It is used in the extraction of gold and platinum.
• It is used in sterilising drinking water.
• It is used in the preparation of poisonous gases such as phosgene , tear gas , mustard gas.

Titanium is called a strategic element.

Important Points:

• It is also known as wonder element or metal of future. 
• It is a transition element with the symbol Ti and the atomic number 22. 
• It is a lightweight, high-strength, low-corrosion metal and is used as an alloy for parts in high-speed aircraft. 

Silver nitrate, AgNO₃ is also known aslunar caustic.

Important Points:

• When silver nitrate comes in contact with skin or clothes, it decomposes into metallic silver and thus leaves black stains.
• It decomposes on exposure to light, hence the reason it is stored in brown bottles. 
• The ammoniacal solution of AgNO₃ is known as Tollens reagent, which is used to distinguish between aldehyde and ketone.

Option Explanation:

Hydrated zinc sulphate is also known as white vitriol, Its chemical formula is ZnSO₄.7H₂O., 

It is used in the preparation of lithopone(ZnS + BaSO₄).

Important Points:

• Zinc phosphide, Zn₃P₂ is used as a rodenticide.
• The strong smell of substance that is used in the colouration or painting is zinc phosphate, Zn₃(PO₄)_{2 .}
• Zinc oxide, ZnO is also known as philosopher’s wool. It is an amphoteric oxide.

Plaster of Paris is a hemihydrate of calcium sulphate(CaSO₄.1/2H₂O) .

Important Points:

• Chemical formula - CaSO₄.1/2H₂O
• Plaster of Paris is a white powder and on mixing with water, it changes to gypsum (CaSO₄ .2H₂O).

Uses of Plaster of Paris:

• It is used in the hospital for setting fractured bones in the right position to ensure correct healing.
• It is also employed in dentistry, in ornamental work and for making casts of statues and busts.
• Plaster of Paris is used for making toys, materials for decoration and for making surfaces smooth.

Red phosphorus is used in the manufacture of safety matches.

Important Points

• Red phosphorus possesses iron grey lustre. 

• It is odourless, nonpoisonous and insoluble in water as well as in carbon disulphide. 

• White phosphorus is more reactive than red phosphorus.

• Red phosphorus used in some fireworks and explosives. 

Option Explanation

White phosphorus is least stable.

Important Points:

• White phosphorus is a translucent white waxy solid. 
• It is poisonous, insoluble in water but soluble in carbon disulphide and glows in dark (chemiluminescence). 
• It has a garlic like odour. 
• In presence of light, white phosphorus turns yellow. 

Nitric acid is prepared by the Ostwald process.

Important Points:

• It is a strong oxidizing agent and a colorless liquid. 
• In aqueous solution, nitric acid behaves as a strong acid giving hydronium and nitrate ions. 
• It is used for the preparation of nitroglycerin, trinitrotoluene and other organic nitro compounds. 
• When it is combined with hydrochloric acid, aqua Regia (3:1 mixture of hydrochloric acid and nitric acid) is formed.

Benzoic acid is present in grass.

Important Points:

• An acid is a substance that furnishes hydrogen ions (H⁺) when dissolved in water. 
• Some examples of acids are- Hydrochloric acid (HCl) in gastric juice, Carbonic acid (H₂CO₃) in soft drinks, Ascorbic acid (vitamin C) in lemon and many fruits, Malic acid in apples, Benzoic acid in grass, Tannic acid in tea, Nitric acid (HNO₃) used in laboratories, Glutamic acid in wheat. 

Sulphuric acid is a diprotic acid because it can donate two protons.

Important Points:

• A diprotic acid is an acid that can donate two protons.
• The term "diprotic" comes from the Greek word "di", which means "two".
• Some common diprotic acids include sulphuric acid (H2SO4), carbonic acid (H2CO3), and oxalic acid (H2C2O4).
• Diprotic acids are important in a variety of applications, including industrial processes, cleaning products, and fertilizers.

Only 1 and 3 are correct. 

Important Points :

• Acids are sour to taste.
• They turn red litmus to blue.
• Hydrogen gas is released when acids react with metal.
• The acid and the base neutralize each other to form the corresponding salt and water.

A copper vessel when exposed to humid air for a long time acquires a dull green coating on its outer surface. 

Important Points :

• The green material is a mixture of copper hydroxide (Cu(OH)2) and copper carbonate (CuCO3). 
• This mixture is also known as basic copper carbonate. Reaction that takes place is- 2Cu+H2O+CO2 +O2→Cu (OH)2 + CuCO3