Let's first see the meanings of the given words:
Unless = (conjunction) used to show “something can only happen in a particular situation.
Even if = (conjunction) used for showing “despite the possibility”.
Even though = (conjunction) means despite the fact that.
Because = (conjunction) means “for the reason that”.

Now let's find out the correct fit for the blank:

• “Unless” as a conjunction is used to say that something can only happen or be true in a particular situation. It is used when a negative sense is attached to the main clause of the sentence. Thus, option A is incorrect.

• “Even if” as a conjunction is used to show the sense of “despite the possibility”. Thus, option B is incorrect.

• “Because” as a conjunction means “for the reason that”. Thus, option D is incorrect.

• "Even though" as a conjunction is used to show the sense of “despite the fact that”. Here in the given sentence, it is used to mention that speaker (i.e. “I”) won the chess “despite the fact” that he was out of practice.

Thus, "Even though" becomes the correct word to fill in the blank.
Hence, option C is the correct answer.

Let's first see the meanings of the given words:-

Advanced = (adjective) at a high or difficult level.

Fast = (adjective) moving or able to move quickly.

Rapid = (adjective) happening quickly or in a short period of time.

Crash = (noun) an accident in which a vehicle hits something

• "Advanced" as an adjective means at a high or difficult level. Here in the given sentence, it is used before the noun “class” to show that one who passes the test successfully will be sent to a class of a higher or more difficult level.

Thus, "Advanced" becomes the correct word to fill in the blank.

Hence, option A is the correct answer.

Let us understand the meaning of the given words:-

• With = (preposition) in the company or presence of someone/something.

• Within = (adverb) inside.

• Where = (adverb) in or to what place or situation.

• Without = (preposition) not having, experiencing or showing something.

Now let's find out the correct fit for the blank:

• “With” as a preposition means in the company or presence of someone/something. Thus, option A is incorrect.

• “Within” as an adverb means “inside”. Thus, option B is incorrect.

• “Where” as an adverb means “in or to what place or situation”. Thus, option C is incorrect.

• "Without" as a part of idiom “there is no smoke without fire” means if something bad is being said about someone/something, it usually has some truth in it.

• Here in the given sentence, it is used to show that something is true about the news because whenever something bad is being talked about then it has some truth.

Thus, "Without" becomes the correct word to fill in the blank.

Thus, the correct sentence will be: I am sure there is some truth in the news. There is no smoke without fire.

Hence, option D is the correct answer.

Let us understand the meaning of the given words:-

• Ingredients = (noun) things from which something is made, especially one of the foods that are used together to make a particular dish.

• Requirements = (noun) something that you need or want.

• Essentials = (noun) something that is needed in a particular situation.

• Materials = (noun) a substance that things can be made from.

Now let's find out the correct fit for the blank:

• “Requirements” as noun means something that you need or want. Thus, option B is incorrect.

• “Essentials” as noun means something that is needed in a particular situation. Thus, option C is incorrect.

• “Materials” as noun means a substance that things can be made from. Thus, option D is incorrect.

• "Ingredients" as noun means things from which something is made, especially one of the foods that are used together to make a particular dish. Here in the given sentence, it is used to show that it is compulsory to list the things on the label from which the product is made.

Thus, "Ingredients" becomes the correct word to fill in the blank.

Thus, the correct sentence will be:

It is mandatory for information about the ingredients of the product to be given on the label.

Hence, option A is the correct answer.

Let us understand the meaning of the given words:-

• Compound = (adjective) formed of two or more parts.

• Usual = (adjective) something that happens or is done most of the time or in most cases

• Global = (adjective) covering or affecting the whole world.

• Simple = (adjective) something that is not complicated.

Now let's find out the correct fit for the blank:

• “Compound” as an adjective refers to something that is formed of two or more parts. Thus, option A is incorrect.

• “Usual” as an adjective means something that happens or is done most of the time or in most cases. Thus, option B is incorrect.

• “Simple” as an adjective means something that is not complicated. Thus, option D is incorrect.

• "Global" as an adjective means covering or affecting the whole world. Here in the given sentence, it is used to qualify the noun “interest”. It means development of solar energy covers the interest of whole world.

Thus, "Global" becomes the correct word to fill in the blank.

Thus, the correct sentence will be:

The development of solar energy is of global interest, as it is a possible substitute for oil.

Hence, option C is the correct answer.

Let us understand the meaning of the given words:-

* At = (preposition) is used to show where something/someone is or where something happens.

* By = (preposition) is used for showing how or in what way something is done.

* Of = (preposition) is used after adjectives to connect with something it relates to.

* To = (preposition) is used for “towards something”

Now let's find out the correct fit for the blank:

* “At” as a preposition is used to show “location” of something/someone. Thus, option A is incorrect.

* “By” as a preposition is used for showing way of doing things. Thus, option B is incorrect.

* “To” as a preposition is used for showing the direction of something. Thus, option D is incorrect.

* "Of" as a preposition is used after some adjectives before mentioning someone/something that a feeling relates to.

* Here in the given sentence, it is used after the adjective (tired) to show that the act of “reminding” has been done too many times. The sentence is trying to relate this act with the feeling of “tiredness”.

Thus, "Of" becomes the correct word to fill in the blank.

Thus the correct sentence will be: I am tired of reminding you to clean your room.

Hence, option C is the correct answer.

Let us understand the meaning of the given words:-

• Accuse = to say that someone has done something wrong or is guilty of something.

• Assure = to tell someone that something is definitely true or is going to happen.

• Admire = to respect someone for what they have done.

• Admit = to agree that something is true.

Now let's find out the correct fit for the blank:

• “Assure” is used particularly in the context of “definitely true” Thus, option B is incorrect.

• “Admire” is used in the sense of “respect someone”. Thus, option C is incorrect.

• “Admit” is used in the sense of “confess”. Thus, option D is incorrect.

• "Accuse" is used in sense of “saying someone is guilty”. Here in the given sentence, it means “you” should not say that “he” is guilty of doing something wrong to “you”.

Thus, "Accuse" becomes the correct word to fill in the blank.

Thus the correct sentence will be: Do not accuse him; he has done no harm to you.

Let us understand the meaning of the given words:-

* Distinguish = to recognize the difference between two people or things

* Distract = to take someone’s attention away from what they are trying to do.

* Divert = to make someone/something change direction

* Detect = to discover or notice something.

Now let's find out the correct fit for the blank:

* “Distract” is used particularly in the context of “taking away one’s attention” Thus, option B is incorrect.

* “Divert” is used in the sense of “change in direction”. Thus, option C is incorrect.

* “Detect” is used in the sense of “notice or discover”. Thus, option D is incorrect.

* "Distinguish" is used in sense of “differentiate”. Here in the given sentence, the person is asking to differentiate one shade from the other.

Thus, "Distinguish" becomes the correct word to fill in the blank.

Thus the correct sentence will be:

Can you distinguish between these two shades of green?

The blank needs to be filled with a noun.

Let us understand the meaning of the given words :-

Bitterness= sharpness of taste; lack of sweetness, having a harsh, disagreeably acrid taste, like that of aspirin.

Stillness= total lack of movement or changing of position.

Eagerness= in an earnest, ardent, or eager way; keenness.

Thickness= the quality or condition of being thick.

The sentence talks about that the prisoner was angry, upset and his voice was harsh.

Thus, ‘bitterness’ is the most suited one.

The correct sentence is: The prisoner was very upset and angry and there was bitterness in her voice.

Hence, option A is the correct answer.

Let us understand the meaning of the given words:-

* Prescribed = (of a doctor) to tell someone to take a particular medicine or do a particular treatment.

* Remembered = to have an image in your memory of an event.

* Delighted = very pleased

* Appeared = to arrive at a place OR to take part in a film/play

Now let's find out the correct fit for the blank:

*  “Prescribed” is used particularly in context of “doctor giving an advice”. Thus, option A is incorrect.

* “Remembered” is used in the context of “memory”. Thus, option B is incorrect.

* “Delighted” is used in the sense of “being pleased”. Thus, option C is incorrect.

* "Appeared" is used for arriving at a place. Here in the given sentence, “headmaster” is arriving on the stage for a speech.

Thus, "Appeared" becomes the correct word to fill in the blank.
The correct sentence will be: The headmaster appeared on the stage and gave a short speech.

Hence, option D is the correct answer.