Explore topic-wise InterviewSolutions in .

Correct option is (d) S + O2 → SO2

The explanation is: Only the reaction; S + O2 → SO2 is a chemical combination reaction, WHEREAS X + YZ → XZ + Z and 2F2 + 2OH^– → 2F^– + OF2 + H2O are disproportionation REACTIONS and 2NaH → 2Na + H2 is a chemical decomposition reaction.

Correct answer is (b) False

Easy explanation: The above STATEMENT is CONSIDERED to be false because it is a decomposition reaction as SODIUM HYDRIDE is BROKEN down into Sodium and hydrogen. A combination of reaction results in the formation of a new compound instead of breaking down.

The CORRECT answer is (c) disproportionate REACTION

The best I can explain: Disproportion reaction occurs when an element in a compound after reactions splits into two different OXIDATION States i.e. it is reduced and oxidized. In the above reaction. FLORINE is reduced as WELL as oxidized, so it is a disproportionate reaction.

Right answer is (b) DISPLACEMENT reaction

The explanation is: In a displacement reaction, a metal or a non-metal, in a COMPOUND can be displaced by ANOTHER metal in the uncombined state. So the above reaction X + YZ → XZ + Z, is a displacement reaction.

The CORRECT choice is (a) true

The best EXPLANATION: Yes, the above statement is true, because, in displacement reactions, there are TWO types. ONE is the metal displacement and the other is nonmetal displacement, both of them are redox reactions.

The correct answer is (c) DISPROPORTIONATION

The BEST I can explain: Disproportionation reactions are a special type of redox reactions. In this type of redox reactions, a single COMPOUND undergoes oxidation and REDUCTION at the same time. The breakdown of hydrogen peroxide into water and hydrogen, the same THING happens.

The correct ANSWER is (d) Mercury (II) chloride

The explanation: The system that exhibits variable oxidation States in SPECIFIED Roman NUMERALS within parentheses after the symbol is the NAME of the element is known as stock notation. Mercury (II) chloride is in stock notation.

The correct answer is (b) decomposition

Explanation: The REVERSE reaction of a combination reaction as a decomposition reaction. In a decomposition reaction, the breakdown of a compound happens into two or more COMPONENTS, here WATER is BROKEN down into hydrogen and oxygen, so it is a decomposition reaction.

Right option is (d) displacement

The BEST explanation: An ION in a COMPOUND is REPLACED by an ion of other element is a sort of displacement reaction. Here the ions are SALTS, the exchange of salts between zinc and copper is an example of a displacement reaction.

Correct option is (a) combination

The explanation is: The CHEMICAL combination reaction results in the formation of a NEW compound from TWO ELEMENTS substances. The above formation of Sulphur dioxide from Sulphur and oxygen is a type of combination reaction.

The correct answer is (b) copper (I) oxide

Easy explanation: The elements exhibiting different OXIDATION States i.e. are DENOTED by Roman numeral such as I, II, III, IV ETC, within parenthesis after the symbol or name of the element this is known as stock NOTATION.

The CORRECT answer is (c) 5/2

The explanation is: the AVERAGE Oxidation state of elements in a compound is the average of the DIFFERENT oxidation States. The average oxidation state of S in Na2S6O6 is X. 2(1) + 4x + 6(-2) = 0; x = 5/2. The average Oxidation state of sulfur here is 5/2.

The correct answer is (a) -3, 5

To EXPLAIN: Dividing into two parts OXIDATION number of N in NH4^+ is x; x + 4*1 = +1; x = -3, oxidation number of N in NO3^– is y; y + 3*-2 = -1; y = 5. The oxidation States of NITROGEN in this compound are -3 and 5 RESPECTIVELY.

Correct choice is (d) 6

For explanation I would SAY: The oxidation states of oxygens in CRO5 are -1, -1, -1, -1 and -2. The oxidation state of Cr is given by x. Therefore x + 4(-1) + (-2)(1) = 0. X = 6. The oxidation state of CHROMIUM in chromium PEROXIDE is 6.

Right CHOICE is (d) 0, 2, 2

Explanation: The structure of C3O2 is given as O=C=C=C=O. Where the OXIDATION number of CARBON beside oxygen is +2 due to oxygen’s -2 oxidation STATE. And the middle carbon’s oxidation is 0, due to +2 charge on it’s both sides.

Right answer is (C) -1

For explanation: In all compounds EXCEPT ionic metal HYDRIDE the OXIDATION number of hydrogen is +1. But in metal HYDRIDES like sodium hydride, magnesium hydride, calcium hydride, etc, the oxidation number of hydrogen as -1.

The CORRECT answer is (b) 0

Easy EXPLANATION: All elements in the elementary STATE have an oxidation number of zero. So helium element also has an Oxidation state of zero. It is one of the most IMPORTANT points for determining the oxidation number.

Correct choice is (a) true

The best explanation: An ELEMENT may have different values of oxidation number DEPENDING upon the nature of the compound in which it is present. Ozone molecule has three oxygens and the oxidation NUMBERS of them are 1, – 1 and 0.

Right choice is (d) sodium hydride

The explanation: MOLECULES of most ELECTRONEGATIVE elements, compounds having an element in the highest oxidation state and OXIDES of metals and nonmetals are examples of oxidising AGENTS. But sodium hydride is a metallic hydride, so it is not an oxidizing AGENT.

Right answer is (b) false

Explanation: OXIDISING agent is ALSO known as an oxidant, the oxidation NUMBER of an oxidant decreases in a Redox reaction whereas the oxidation number of REDUCTANT increases in a reaction. REDUCING agent is known as a reductant.

Right choice is (d) Zn>Cu>Ag

For explanation I WOULD say: Metal activity series or electrochemical series is a series in the decreasing order of metals which are active during a CHEMICAL reaction comparatively with each other. Here, ZINC’s activity is GREATER than Copper’s activity and Copper’s activity is greater than that of SILVER.

The correct OPTION is (a) copper rod is DIPPED in silver NITRATE solution

The explanation: When a copper rod is dipped in silver nitrate solution, a redox reaction occurs between Copper and an aqueous solution of silver nitrate. So the intensity of blue COLOUR increases gradually as silver DEPOSITS on the rod.

Right OPTION is (a) copper

For explanation: OXIDANT or OXIDIZING agent is a chemical substance which can accept one or more electrons and causes oxidation of some other SPECIES. Here to accept electrons from zinc, so copper is an oxidizing agent.

The CORRECT answer is (b) oxidation

Easy explanation: Oxidizing AGENT is the ACCEPTOR of electrons and the reducing agent is a DONOR of the electrons, where oxidation is termed by loss of electrons by any species and REDUCTION is gain of electrons by any species.

The CORRECT choice is (b) tin

Easy explanation: Tin changes is oxidation state from + 2 to + 4. Increase in oxidation number indicates Oxidation reaction. Oxidation is the loss of ELECTRONS by an ATOM, ion or molecule, it is also KNOWN as the de^–electronation.

The correct option is (b) REDUCTION

Easiest explanation: Reduction is a chemical PROCESS, which involves the addition of hydrogen or an element or compound for the removal of oxygen from a compound. An EXAMPLE of reduction is a chemical reaction;

H2 + F2 → 2HF.

The correct answer is (c) redox

Easy EXPLANATION: Chemical reactions which involves both oxygen as WELL as reduction PROCESS simultaneously are known as redox reactions. The above given REACTION involves both OXIDATION and reduction reactions, so it is a Redox reaction.

Correct OPTION is (c) addition of oxygen

Easiest EXPLANATION: OXIDATION is the same as the addition of oxygen or removal of hydrogen where reduction is the addition of hydrogen or removal of oxygen. Oxidation is CAUSED by an oxidising agent and reduction is caused by a reducing agent.

Correct option is (B) OXIDATION

To explain I would say: ADDITION of electronegative element or removal of any other electropositive element is also considered as a process that INVOLVES oxidation. Here, sulphur is an electronegative element. So the formation of zinc sulphide is an Oxidation reaction.

The correct choice is (a) decrease

The best EXPLANATION: The OXIDATION number is recharged in which an atom appears to have when all the atoms are removed from it as ions. It may have +ve or -ve SIGN. REDUCTION results in a decrease in the oxidation number.

Correct answer is (a) true

Easy explanation: OXIDATION is the loss of electrons by an ATOM, ion or molecule. it is ALSO KNOWN as de^–electronation. Zn → Zn^2+ + 2e^–, the loss of electrons from ZINC i.e. formation of zinc is an example of oxidation.