Chemistry Questions

Q:

The function of nitrogen in air is 

A) to make air a moderate supporter of combustion B) to maintain the density of air constant
C) to prevent the hydrogen in air from exploding D) to reduce the poisonous nature of ozone in air
 
Answer & Explanation Answer: A) to make air a moderate supporter of combustion

Explanation:

If air contained all oxygen and no nitrogen, everything would have burnt off

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Q:

What name is given to the bond between water molecules?

A) Polar B) Polar covalent
C) Hydrogen D) None of the above
 
Answer & Explanation Answer: C) Hydrogen

Explanation:

The name given to the bond between water molecules is a hydrogen bond. These bonds occur between the slightly negative oxygen of one water molecule and the slightly positive hydrogen of another water molecule. Hydrogen bonding gives water special physical properties.

 

The differences in electronegativity between hydrogen and oxygen lead to an unequal sharing of electrons. Electronegativity measures how strongly an atom attracts electrons. Oxygen, with its higher electronegativity, pulls on the shared electrons more, giving the oxygen atom a partial net negative charge. The shared electrons spend less time with the hydrogen atoms; therefore, the hydrogen regions of water have partial positive charges.

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Q:

Rank these compounds by boiling point- Pentane, Propane and Hexane.

A) Pentane > Propane > Hexane B) Propane > Pentane > Hexane
C) Hexane > Pentane > Propane D) Propane > Hexane > Pentane
 
Answer & Explanation Answer: C) Hexane > Pentane > Propane

Explanation:

The boiling point of the compounds depend on the number of carbons in them. Hexane has 6, Pentane has 5 and Propane has 3 carbons. As Hexane is with 6 carbons it has highest boiling point and next Pentane with 5 and lowest Propane with 3. 

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Q:

Nucleons are

A) protons and neutrons B) neutrons and electros
C) protons and electrons D) protons, neutrons and electrons
 
Answer & Explanation Answer: A) protons and neutrons

Explanation:
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Q:

The soaps used in shaving cream are 

A) Calcium soaps B) lead soaps
C) soft soaps D) hard soaps
 
Answer & Explanation Answer: C) soft soaps

Explanation:
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Q:

What types of orbital overlap occur in Cumulene?

Answer

A cumulene is a hydrocarbon with three or more cumulative double bonds. They are analogous to allenes, only having a more extensive chain. The simplest molecule in this class is butatriene, which is also called simply cumulene.


 


The carbons on the ends are sp² hybridized, with a p-orbital for the 'second' bond in the double bond with their neighboring carbons.


They have those sp² orbitals overlapping with the s from the hydrogen, and they have a p overlapping in the pi bond with the neighboring carbon. They also have a sigma bond with the neighboring carbon I'll get to.


The middle carbons each have two pi bonds with their neighbors, leaving sp hybridiaztion for the rest. So they have sp/sp² with the end carbons, and sp/sp with each other. (And they also have p/p in the pi bonds).


 


All orbital overlappings in Cumuene are :


* s/sp²


* p/p


* sp/sp²


* sp/sp

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Q:

Which path through the carbon cycle is possible?

A) Animal ----> Plant ----> Atmosphere B) Plant ----> Animal ----> Atmosphere
C) Atmosphere ----> Plant ----> Animal D) Plant ----> Atmosphere -----> Animal
 
Answer & Explanation Answer: B) Plant ----> Animal ----> Atmosphere

Explanation:

During daylight hours, plants capture carbon dioxide from the atmosphere and use it to make carbohydrates which is stored as starch in the plant. Animals feed on the plants and extract the carbohydrates through their digestive system. The carbohydrates, namely glucose, are used by the animals for production of ATP through cellular respiration.

 

Cellar respiration in the animals produces carbon dioxide as a waste product. The carbon dioxide is released into the atmosphere, from where it is again captured by plants and the cycle is repeated.

 

Hence, option B) Plant ----> Animal ----> Atmosphere is the path possible in carbon cycle.

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Q:

Which of the following is a Decomposition Reaction?

A) 2HgO ----> 2Hg + O2 B) 6NaNO3 ----> 6NaNO2 + 3O2
C) ZnCO3 ----> ZnO + CO2 D) All the above
 
Answer & Explanation Answer: D) All the above

Explanation:

All the given reactions are Decomposition reactions.

Decomposition reaction is a reaction in which only one reactant is splitted into two or more products.

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