Chemistry MCQ Quiz - Objective Question with Answer for Chemistry - Download Free PDF

The correct answer is long, saturated carbon chains.

Key Points

• Explanation:-

  

 

• Polyunsaturated fatty acids make up the majority of vegetable oils. The hydrogenation process converts unsaturated fatty acids to saturated fatty acids.
  • Saturated and unsaturated fatty acids are liquids and solids, respectively. Hydrogenation of vegetable oils is accomplished by injecting hydrogen gas into the heated oil while a reduction catalyst is present.
  • In the presence of a catalyst, hydrogenation decreases unsaturated fatty acids in triglycerides by attaching hydrogen atoms at the location of unsaturation.
  • Hydrogenation of vegetable oils is accomplished by injecting hydrogen gas (H2) into the heated oil in the presence of a catalyst (powdered nickel).
  • The heating of vegetable oils in the presence of nickel catalyst converts the unsaturated fat to saturated fats called vegetable ghee also known as Vanaspati ghee.
  • Vegetable oil is heated after hydrogenation, and the catalyst is recovered through filtration.

Key Points

• The greenhouse effect is the process by which radiations from the sun are absorbed by greenhouse gases and not reflected back into space.
• This insulates the surface of the earth and prevents it from freezing.
• Due to the increased levels of greenhouse gases, the temperature of the earth has increased to a very high level due to various factors. This has led to several drastic effects.
• The main cause of this environmental issue is the increased volumes of greenhouse gases such as carbon dioxide and methane released by the burning of fossil fuels, emissions from vehicles, industries, and other human activities.

The correct option is Liquid.Key Points

•  The state of matter that has definite volume but cannot form a definite shape is liquid.
• The liquid is the second state of matter.
• The particles or atoms in a liquid compound are not closely packed.
• It cannot form a definite shape like solids.
• It can be measured in volume.
• The particles in liquid compounds are away from each other.

Additional Information

•  Gas is the third state of matter.
• It cannot form a definite shape and volume.
• The particles in gaseous compounds are far away from each other.
• Solid is the first state of matter and has a particular shape.
• Solid compounds have close packing of atoms.
• Plasma is the fourth state of matter.

The correct option is 1 i.e., Hydrogen gas and iron chloride are produced.

• Hydrogen gas and iron chloride are produced when dilute hydrochloric acid is added to iron filings.
• Acids lose their acidity when mixed with a base.
• Acids and metal sulphides form salt and hydrogen sulphide.
• Some Acids are highly corrosive in nature which means that they corrode or rust metals.
• Acids turn the pink colour of Phenolphthalein to colourless.
• Weak Acids like Carbonic Acid doesn’t act with any metal.

The chemical name of Chloroform is Trichloromethane.Key Points 

• Chloroform or Trichloromethane (CHCl3) is a colorless, dense, and non-flammable liquid that is produced on a large scale as a precursor to PTFE (Teflon) and refrigerants.
• It has a somewhat sweet taste and a pleasant smell, and it was used as an anesthetic in the 19th and early 20th century, but it was banned for this use due to its harmful health effects.

Additional Information 

• ​Acetic Acid: Its chemical formula is CH3COOH. It is a colorless liquid organic compound that gives vinegar its sour taste and pungent smell.
  • It's used in the production of chemicals and for food preservation.
• Calcium Carbonate: Its chemical formula is CaCO3. It's a white insoluble solid occurring naturally as chalk, limestone, marble, and forming mollusk shells and stony corals.
• Sodium Bicarbonate: Its chemical formula is NaHCO3. It's a white crystalline solid, but often appears as a fine powder.
  • It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is known as nahcolite. Sodium bicarbonate is commonly known as baking soda.

The correct answer is Sodium carbonate.

Explanation:

• Washing soda is a chemical compound with the formula Na₂CO₃, known as sodium carbonate, and it's a salt of carbonic acid.
• Properties of a Washing soda:
  • It is a transparent crystalline solid.
  • It is one of the few metal carbonates which are soluble in water.
  • It is alkaline with a pH level of 11, it turns red litmus to blue.
  • It has detergent properties or cleansing properties because it can remove dirt and grease from dirty clothes, etc.
  • It attacks dirt and grease to form water-soluble products, which are then washed away on rinsing with water. 

Important Points

Some common chemical compounds with their common names are:

Chemical Compounds	Common Names	Chemical Formulas
Sodium Bicarbonate	Baking Soda	NaHCO3
Calcium ChlorohypoChlorite	Bleaching Powder	Ca(ClO)2
Sodium Hydroxide	Caustic Soda	NaOH
Sodium Carbonate	Washing Soda	Na2CO3 .10 H2O
Carbon Dioxide	Dry Ice	CO2
Copper Sulphate	Blue Vitriol	CuSO4
Ferrous Sulphate	Green Vitriol	FeSO4
Sulphuric Acid	Oil of vitriol	H2SO4
Calcium Sulphate Hemihydrate	Plaster of Paris	(CaSO4. 1/2H2O)
Calcium Sulphate Dihydrate	Gypsum	CaSO4.2H2O
Calcium Hydroxide	Slaked Lime	Ca(OH)2
Chile Saltpeter	Sodium nitrate	NaNO3
Saltpetre	Potassium nitrate	KNO3
Muriatic acid	Hydrochloric acid	HCl

 

K2CO3 or potassium carbonate is known as pearl ash.

• Pearl ash, in ancient times, was created by baking potash in a kiln in order to remove impurities. The remaining fine, white powder was pearl ash.
• Potassium carbonate is an inorganic compound and a white salt which is soluble in water.
• It is mainly used in the production of glass and soap.

Additional Information

Chemical Formula	Chemical Name	Common Name
Na2CO3	Sodium Carbonate	Washing soda
NaHCO3	Sodium bicarbonate	Baking soda
K2CO3	Potasium carbonate	Pearl ash
CaCO3	Calsium carbonate	Limestone

The correct answer is Lactic Acid.

Key Points

• Lactic acid is present in Sour milk or curd.
• The sourness of the milk is due to the presence of lactic acid.
• Human beings feel tired due to the accumulation of lactic acid in the muscles.​

Additional Information

Natural source	Acid
Vinegar	Acetic acid
Orange	Citric acid
Tamarind	Tartaric acid
Tomato	Oxalic acid

 Key Points

• Atomic Mass of the Hydrogen = 1
• Atomic Mass of the oxygen = 16

Explanation:

1 mole of hydrogen = 1gm

1 mole of oxygen = 16gm

Water (H2O) = 2 Hydrogen atoms + 1 Oxygen atom

2 mole of hydrogen = 2gm

1 mole of oxygen = 16 gm

The ratio of the mass of Hydrogen: Ratio of mass of Oxygen =  2/16 = 1/8 

The ratio of the mass of Hydrogen to the mass of Oxygen in water is always 1:8.

• The number of water molecules present is washing soda is 10.
• We know the molecular formula for Washing Soda is Na₂CO₃.10H₂O.
• Recrystallisation of Sodium Carbonate (Na₂CO₃) gives washing soda.
• In a Washing soda, water is present in the form of crystals.

The correct answer is Vermilion.

• Mercury Sulfide is also known as Vermilion.
• It is a chemical compound composed of the chemical elements mercury and sulfur.
• The chemical formula of Mercury sulfide is HgS.
• It is dimorphic with two crystal forms:
  • Red cinnabar
  • Black metacinnabar

Additional Information

• Marsh Gas is the common name of Methane with the formula of CH₄.
• Mohr's Salt is the common name of Ammonium Ferrous Sulphate with the formula of (NH₄)2Fe(SO₄)₂(H₂O)₆.
• Potash Alum is the common name of Potassium Aluminium Sulphate with the formula of KAl(SO₄)₂.

The correct answer is Double displacement reaction.

Concept:

Chemical reaction:

• It is a process in which one or more substances, the reactants, are converted to one or more different substances, the products.
• A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Explanation:

• Double displacement reaction: 

• It is a chemical reaction in which two compounds react and exchange their ions forming new products. 
• This reaction often results in the formation of an insoluble compound called a precipitate. 
• Such reactions are represented by equations of the following form: A⁺B^- + C⁺D^- → A⁺D^- + B^-C⁺

​In the given chemical reaction: 

NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

The reactants NaCl and AgNO₃ have exchanged their ions to form NaNO3  and AgCl. 

Thus, it is an example of a double displacement reaction.^​

^{Additional Information}

Types of Chemical Reactions:

Combination reaction:

• Two or more elements or compounds combine together to form a single compound.
• Such reactions are represented by equations of the following form:     A + B → AB.

Decomposition reaction:

• The opposite of a combination reaction, a complex molecule breaks down to make simpler ones.
• Such reactions are represented by equations of the following form: AB → A + B.

Displacement reaction:

• One element takes place with another element in the compound.
• Such reactions are represented by equations of the following form: A + BC → AC + B.

Redox reaction:

• It is a reaction in which one species is reduced and the other is oxidized. 
• Reduction means losing Oxygen or gaining hydrogen 
• Oxidation means gaining oxygen or losing hydrogen. 

Explanation:

• Calcium hydroxide is sparingly soluble in water producing an alkaline solution known as limewater.
• Calcium Carbonate is a chemical compound found commonly in rocks as minerals and is the main component of pearls and the shells of marine organisms, eggs, etc.
• When carbon dioxide gas is passed through or over limewater, it turns milky due to the formation of calcium carbonate.
• In the chemical reaction it can be shown as :

\(\rm \underset{Lime\ water}{Ca (OH)_2} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{CaCO_3 \ (g)}\)Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" id="MathJax-Element-1-Frame" role="presentation" style="display: inline; position: relative;" tabindex="0">Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" role="presentation" style="display: inline; position: relative;" tabindex="0">Ca(OH)2

• However, when an excess of CO2 ​is passed through this solution, the milkiness disappears. This is due to the formation of calcium bicarbonate which is colorless and soluble in water.

Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" role="presentation" style="display: inline; position: relative;" tabindex="0">​\(\rm \underset{Lime\ water}{Ca (OH)_2} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{CaCO_3 \ (g)}\)​\(\rm \underset{Lime\ water}{Ca CO_3} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{Ca(HCO_3)_2 \ (g)}\)Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate\(\rm \underset{Calcium\ Carbonate}{Ca CO_3} \ \ +H_2O+ \ \underset{Carbon \ Dioxide}{CO_2 \ (g) } \ \longrightarrow \ \underset{Calcium \ bi\ Carbonate}{Ca(HCO_3)_2 \ (g)}\)

 

Additional Information Reaction involved-

CaCO₃ + 2HCl →  CaCl₂ + CO₂ + H₂O

• The evolved gas is carbon dioxide which then passes through lime water and turns it milky.

Ca(OH)₂ + CO₂ → H₂O + CaCO₃  

• Due to formation of these compounds
• when excess CO₂ is passed

CaCO₃ + H₂O + CO₂ →  Ca(HCO₃)₂ 

• Bicarbonate is formed which again clears the solution

Mistake Points

•  Do not confuse Calcium carbonate and calcium bicarbonate.
• One produces white colour while the other makes it colourless.

• Aluminium (Al) metal reacts with steam to form a metal oxide and hydrogen.
• This reaction can be given as

2Al + 3H₂O (g) → Al₂O₃ + 3H₂ (g)

• Other metals of this type are Iron (Fe) and Zinc (Zn).

• But these metals do not react with either hot or cold water.

Silver, Lead and Copper do not react with water whether the water is in the form of liquid or gas.

pH of some common aqueous solutions

Solution	pH
1M HCl	0.0
Gastric juice	1.0
Lemon juice	2-3
Vinegar	3.0
Tomato juice	4.1
Pure water, sugar solution	7.0