Punjab Chemistry 2017 Paper 4 — Solved MCQs

Question 1

Alkali metals give hydrides:

Accepted Answer

B. lonic — Ionic hydrides are formed due to highly active metals which are all more electropositive in nature. Alkali metals are more electropositive as they easily lose its outermost electrons. Thus they form the ionic hydrides.

Question 2

Which of the following sulphates is insoluble in water?

Accepted Answer

A. Barium sulphate — Barium sulphate is insoluble in water for its high lattice energy as well as low hydration energy, which is the ionic compound of these chemical particles. Decreased lattice energy along with the greater hydration energy consumption leads to higher solubility of chemical particles.

Question 3

Boric acid cannot be used as:

Accepted Answer

D. For soda bottles — Boric acids can't be used for soda bottles because it is conside as weak acid.

Question 4

The brown gas formed when metal reduces HNO3 is :

Accepted Answer

B. NO2 — The brown gas formed when HNO3 is reduced by metal to form nitrogen dioxide which is a poisonous brown gas with an irritating odour.

Question 5

Which of the followings is a typical transition metal:

Accepted Answer

A. Co — The elements below have properties that are typical of transition elements: chromium, Cr. Manganese, Mn. iron, Fe, Co.

Question 6

The chemist who synthesized urea from ammonium cyanate was:

Accepted Answer

D. Wöhler — Friedrich Wöhler was the first to synthesize an organic compound from an inorganic substance. In 1828, he synthesized urea by slowly evaporating a water solution of ammonium cyanate, which he had prepared by adding silver cyanate to ammonium chloride.

Question 7

One of the following formula of ethyl acetate is:

Accepted Answer

C. CH3COOC2H5 — Ethyl acetate (systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula CH3CO2CH2CH3, simplified to C4H8O2.

Question 8

Which compound is most reactive one?

Accepted Answer

D. Benzene — Due to its high degree of unsaturation, it is highly reactive. Unlike alkenes, it never participates in addition, oxidation, and reduction reactions. For example, benzene won't react with Br, HCl or other reagents to result in carbon-carbon double bonds formation.

Question 9

Which of the following will react with Fehling solution?

Accepted Answer

C. CH-CO-H — Formic acid is the only acid that gives a red precipitate with Fehling's solution. This is because of the presence of aldehyde group type hydrogen in formic acid. Aromatic aldehydes do not give positive results with Fehling's solution. Glucose and fructose both give red precipitate on reacting with Fehling's solution.

Question 10

Which enzyme is involved in fermentation of glucose?

Accepted Answer

A. Zymase — Zymase (also known as alcoholase) is an obsolete term for an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. It occurs naturally in yeasts. Zymase activity varies among yeast strains.

Question 11

Which halogen will react spontaneously with Au(s) to produce Au**?

Accepted Answer

B. Cl2 — Chlorine ( Cl2 ) is the halogen react spontaneously with gold to produce gold ions

Question 12

Which of the following reagents react with both aldehydes and ketones?

Accepted Answer

D. Grignard's reagent — Both aldehydes and ketones react with Grignard reagent to give alcohols.

Question 13

The reagent used to reduce carboxylic group to an alcohol is:

Accepted Answer

A. LiAIH4 — Most reductions of carboxylic acids lead to the formation of primary alcohols. These reductions are normally carried out using a strong reducing agent, such as lithium aluminum hydride (LiAlH4). You can also use diborane (B2H6) to reduce carboxylic acids to alcohols.

Question 14

Sucrose is composed of two monomer units:

Accepted Answer

D. Glucose+Fructose — Sucrose (table sugar) is the most common disaccharide, which is composed of the monomers glucose and fructose. A polysaccharide is a long chain of monosaccharides linked by glycosidic bonds. The chain may be branched or unbranched and can contain many types of monosaccharides.

Question 15

The three elements needed for the healthy growth of plants are:

Accepted Answer

C. N,K,P — ''N, K, P," is correct because nitrogen (N), potassium (K), and phosphorus (P) are essential nutrients for plants. Nitrogen is important for plant growth and leaf development, potassium is involved in various physiological processes, and phosphorus is crucial for energy transfer and cell division.

Question 16

In purification of polluted water the coagulent used is:

Accepted Answer

C. Iron sulphate — Ferric sulfate, aluminum sulfate, or ferric chloride, classed as aluminum or iron salts, are common coagulants for water treatment. A coagulant is a chemical that is used to remove suspended solids from drinking water.

Question 17

Ecosystem is a smaller unit of:

Accepted Answer

D. biosphere — Ecosystem is a smaller unit of biosphere which consists of community of organisms and their interaction with environment i.e., animals, plants and microorganisms which lie in a definite zone and depend on the physical factors such as soil, water, and air.

Punjab Chemistry 2017 Paper 4 — Solved Past Paper with Answers

More Punjab / UHS Solved Papers