Question

#1: The element that loses electrons in a chemical reaction is said to have been which of the following?

Answer 1

#1: The element that loses electrons in a chemical reaction is said to have been which of the following? A. reduced

B. oxidized

C. combusted

D. rusted

**idk, is it reduced or oxidized??

Answer: oxidized. The element that loses electrons increases its oxidation number (becomes more positve or less negative) and this is oxidation.


Which type of reaction occurs if one element gains electrons and another loses electrons?

A. combustion

B. synthesis

C. oxidation-reduction

D. double-displacement

**my answer: C

Yes, oxidation-reduction

#3: What is the oxidation number for phosphorus in H4P2O7?

A. +5

B. +3

C. +1

D. - 1

**my answer: A. +5

This is the way to calculate it 4(+1) + 2x + 7(-2) = 0 => x = +5



#4: What is the oxidation number for phosphorus in Na2HPO3?

A. +5

B. +3

C. +1

D. - 1

**my answer; B. +3

is that right??

Right

2(+1) + 1 + x + 3(-2) = 0 => x = 6 -1 -2 = 3 (positive)

Answer 2

Answer:

For 1: The correct option is B.

For 2: The correct option is C.

For 3: The correct option is A.

For 4: The correct option is B.

Explanation:

• For 1:

There are two types of reaction based on the basis of exchange of electrons.

The reaction in which an element gain electrons is considered as reduction reaction and the species gets reduced in the reaction.

The reaction in which an element looses electrons is considered as oxidation reaction and the species gets oxidized in the reaction.

Hence, the element which looses electrons in a chemical reaction is said to have been oxidized. So, the correct option is B.

• For 2:

Combustion reaction are the chemical reactions in which a hydrocarbon is decomposed to carbon dioxide and water in the presence of oxygen.

Synthesis reaction is the chemical reaction in which two or more compounds combine to form a larger molecule by releasing some by-products.

Oxidation-reduction reaction is the chemical reaction in which one element gains electrons and another element looses electrons. This reaction is known as redox reactions.

Double displacement reactions are the chemical reactions in which exchange of ions takes place.

Hence, the correct option is C.

• For 3:

Oxidation number is the number given to an element in a chemical compound which represents the number of electrons lost or gained by that element.

Oxidation number of hydrogen = +1

Oxidation number of oxygen = -2

Oxidation number of phosphorous in $H_4P_2O_7$ is:

$4(+1)+2x+7(-2)=0\\\\x=+5$

Hence, the correct option is A.

• For 4:

Oxidation number is the number given to an element in a chemical compound which represents the number of electrons lost or gained by that element.

Oxidation number of Sodium = +1

Oxidation number of oxygen = -2

Oxidation number of Hydrogen = +1

Oxidation number of phosphorous in $Na_2HPO_3$ is:

$2(+1)+1+x+3(-2)=0\\\\x=+3$

Hence, the correct option is B.