Chemistry MCQ Quiz - Objective Question with Answer for Chemistry - Download Free PDF
Last updated on May 9, 2024
Latest Chemistry MCQ Objective Questions
Chemistry Question 1:
Vitamin E is also called ______
Answer (Detailed Solution Below)
Chemistry Question 1 Detailed Solution
Concept:
Vitamins:
- Vitamins are organic compounds that are present in minute amounts in natural foodstuffs.
- Most vitamins come from food because the body either does not produce them or produces very little.
- Vitamins are of two types.
- Fat-soluble vitamins- Vitamins A, D, E, K.
- Water-soluble vitamins- Vitamin C and all the B vitamins.
- There are 13 vitamins - A, C, D, E, K, and B vitamins (thiamine, riboflavin, niacin, pantothenic acid, biotin, B6, B12, and folate), each of them have a different job.
- Vitamin A, D, E, K are Fat-Soluble vitamins and are stored in fat cells while vitamins B and C are water-soluble vitamins that are not stored in your body.
- The liver acts as a storage site for vitamin A, D, E, K, and B12 for the times when they may be lacking in the diet.
- Vitamin D acts as a hormone, produced by the kidneys it helps to control the concentration of calcium in the blood and is vital for the development of strong bones.
- Water-soluble vitamins like Thiamine, folate, biotin, riboflavin are synthesized by gut bacteria.
Explanation:
- Vitamin E is a mixture of four vitamins called α, β, γ and δ tocopherols among which α tocopherol is the most active.
- Characteristics:
- Light yellow fat soluble in oils.
- Stable to heat and oxidation.
- Sources are cotton seed oil, maize oil, peanut oil and wheat germ oil.
- Deficiency causes damage to the reproductive system.
Hence, Vitamin E is also called tocopherol.
Additional Information
- Riboflavin is vitamin B2.
- Calciferol is vitamin D.
- Thiamine is vitamin B1.
Chemistry Question 2:
Which one of the following, statements is incorrect about enzyme catalysis
Answer (Detailed Solution Below)
Chemistry Question 2 Detailed Solution
Explanation:
Enzyme catalysis:
⇒ Catalysis is a phenomenon in which the rate of the reaction is altered with the help of a substance called a catalyst (the catalyst does not participate in the reaction; its concentration and composition remain unchanged).
⇒ The substance used to change the rate of the reaction is called a catalyst. Enzymes are a class of catalysts that are responsible for facilitating and increasing the rate of many vital biochemical reactions in plants and animals.
The catalysis in which enzymes act as a catalyst is called enzyme catalysis.
- A single molecule of the enzyme catalyst can transform up to a million molecules of the reactant per second. Hence, enzyme catalysts are said to be highly efficient.
- These biochemical catalysts are unique to certain types of reactions, i.e. the same catalyst cannot be used in more than one reaction.
- The effectiveness of a catalyst is maximum at its optimum temperature. The activity of the biochemical catalysts declines at either side of the optimum temperature.
- Enzymes are mostly proteinous in nature. Enzymes are denatured by ultraviolet rays and at high temperatures.
Chemistry Question 3:
Identify the correct statement regarding oxidation state of Group 15 elements.
Answer (Detailed Solution Below)
Chemistry Question 3 Detailed Solution
The correct answer is option 2, i.e., The stability of +5 oxidation state decreases down the group.
- Out of the given options, the correct statement regarding the oxidation state of Group 15 elements (Nitrogen family) is the stability of +5 oxidation state decreases down the group.
- The stability of +5 oxidation state decreases down the group and that of +3 oxidation state increases, with BiF5 being the only well-characterized Bi (V) compound. Hence, Option 1 is NOT correct while Option 2 is correct.
- This is because of the 'inert-pair effect'.
- Inert-pair effect is the tendency of the two s-electrons to not participate in bonding due to the high energy needed for unpairing them.
- This phenomenon is seen in compounds of post-transition metals (Group 13, 14, 15, and 16).
- The tendency of -3 oxidation state decrease down the group.
- This happens due to the increase in size and metallic character of elements down the group.
- The last member of the Nitrogen family, Bismuth hardly forms any compound with -3 oxidation state.
- Nitrogen is restricted to maximum covalency of 4 because it has 4 orbitals (one s and three p) available for bonding.
- The most common oxidation states exhibited by the Group 15 elements is -3, +3, and +5.
- Nitrogen exhibits +1, +2, and +4 oxidation states also when it reacts with oxygen.
- Phosphorous exhibits +1 and +4 oxidation states in some oxoacids.
Chemistry Question 4:
2-acetoxybenzoic acid is called :
Answer (Detailed Solution Below)
Chemistry Question 4 Detailed Solution
Concept:
Explanation:
- 2-acetoxybenzoic acid is commonly known as aspirin.
- It is prepared by the reaction of acetylation of salicylic acid. It can be achieved by the reaction of salicylic acid with acetic acid in presence of catalyst acids.
- However, the yield is low when acetic acid is used and it can be replaced by acetic anhydride which gives a comparatively much higher yield.
- The acetylation of the phenol group of salicylic acid occurs giving the product Acetylsalicylic acid commonly known as aspirin.
- The reaction is:
Chemistry Question 5:
Transition metals form complexes due to
Answer (Detailed Solution Below)
Chemistry Question 5 Detailed Solution
Explanation:
The position of d-block elements is in between s-block and p-block elements in the periodic table. These d-block elements are called transition elements because they exhibit transitional behaviour between s-block and p-block elements.
- Transition metals are d-block elements with valence shell configuration ns2 (n-1) d(1-10) .
- The transition metals and their ions easily coordinate to a number of negative ions or neutral molecules having lone pairs of electrons to form complexes.
- The reason for this is small size and high nuclear charge of these metals and availability of vacant d-orbitals of suitable energy to accommodate lone pairs of electrons donated by the ligands.
- The cations of the d-block elements have a strong tendency to form complexes with certain molecules or ions called ligands.
So, Transition metals form complexes due to their Small size, Available d orbital and Large ionic charge.
Top Chemistry MCQ Objective Questions
Chemical name of washing soda is:
Answer (Detailed Solution Below)
Chemistry Question 6 Detailed Solution
Download Solution PDFThe 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 |
CaOCl2 |
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 |
Which of the following is called 'Pearl ash'?
Answer (Detailed Solution Below)
Chemistry Question 7 Detailed Solution
Download Solution PDFK2CO3 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
Which acid is present in sour milk?
Answer (Detailed Solution Below)
Chemistry Question 8 Detailed Solution
Download Solution PDFThe 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 |
The ratio of the mass of hydrogen to the mass of oxygen in water is always ________.
Answer (Detailed Solution Below)
Chemistry Question 9 Detailed Solution
Download Solution PDF 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.
When 1 litre of water is cooled from 4°C to 0°C, its volume _____.
Answer (Detailed Solution Below)
Chemistry Question 10 Detailed Solution
Download Solution PDFThe correct answer is increases.
Important Points
- In normal cases, the volume of substances increases on heating and decreases while cooling.
- When 1 litre of water is cooled from 4°C to 0°C volume of water will start increasing this due to water's unique property known as 'Anomalous Expansion of Water'.
- Anomalous Expansion of Water occurs between 4°C to 0°C.
- The density of water is a maximum at 4 °C.
- When water is cooled from 4°C to 0°C, its density decreases.
- The anomalous expansion of water helps preserve aquatic life during very cold weather.
Explanation:
- When water reaches 4°C the molecules have been pushed as close to one another as possible and the density of water becomes precisely 1.00 g/cm³
- When water freezes at 0°C due to the crystal structure the molecules arranged in some structured fashion so a little far apart ended up less dense - 0.93 g/cm3 - and so floats due to buoyancy.
As density decreases the volume increases.
Volume = mass /density.
CO2 when passed in excess, in lime water turns colourless again because of:
Answer (Detailed Solution Below)
Chemistry Question 11 Detailed Solution
Download Solution PDFExplanation:
- 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 :
\(\rm \underset{Lime\ water}{Ca (OH)_2} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{CaCO_3 \ (g)}\)
- 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.
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.
How many water molecules are present in one molecule of washing soda?
Answer (Detailed Solution Below)
Chemistry Question 12 Detailed Solution
Download Solution PDF- 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.
What is the common name of Mercury Sulfide?
Answer (Detailed Solution Below)
Chemistry Question 13 Detailed Solution
Download Solution PDFThe 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.
Which of the following metals reacts with steam to form a metal oxide and hydrogen?
Answer (Detailed Solution Below)
Chemistry Question 14 Detailed Solution
Download Solution PDF- 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.
To which category of reactions does the following chemical reaction belong?
NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)
Answer (Detailed Solution Below)
Chemistry Question 15 Detailed Solution
Download Solution PDFThe 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.