Chemistry Questions

Q:

Which statement best describes electrons?

A) Electrons orbit around the nucleus B) Electrons are composed of protons and neutrons
C) Electrons reside in the nucleus D) Electrons have a positive charge
 
Answer & Explanation Answer: A) Electrons orbit around the nucleus

Explanation:

Electrons orbit around the nucleus is correct about them.

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Q:

When Ionic bonds are formed metallic atoms tend to

A) share electrons B) gain electrons
C) lose electrons D) None of above
 
Answer & Explanation Answer: C) lose electrons

Explanation:

Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.

 

Hence, when Ionic bonds are formed metallic atoms tend to lose electrons and become positive ions

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Q:

What happens when two atoms form a chemical bond?

A) Two atoms fuse together to form a chemical bond B) The atoms share or transfer electrons
C) A chemical bond forms when two atoms transfer or share protons to achieve a stable nucleus D) Like charges in the atoms cause them to stick together
 
Answer & Explanation Answer: B) The atoms share or transfer electrons

Explanation:

All chemistry is based on sharing electrons. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.

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Q:

Identify the metalloid in the following list?

A) Silicon B) Sulphur
C) Scandium D) All of the above
 
Answer & Explanation Answer: A) Silicon

Explanation:

A metalloid is an element with properties between metals and non metals or the mix of both.

The six metalloids are arsenic, silicon, germanium, boron, antimony and tellurium.

 

Hence, silicon is the only metalloid in the given list.

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Q:

Ketchup stored in a tin can may lead to chemical contamination.

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:

The given statement is True.


Ketchup is acidic, having a pH of 3.9. The acidic component, acetic acid, will react with the metal tin. This reaction will result in a metal acetate that will contaminate the ketchup.


 


Hence, The acetic acid in the ketchup will react with the metal tin, forming a metal acetate that will pass into the ketchup which leads to its contamination.

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Q:

The most electronegative element among the following is

A) Oxygen B) Chlorine
C) Nitrogen D) Sodium
 
Answer & Explanation Answer: A) Oxygen

Explanation:

Electronegativity measures an element's ability to form chemical bonds. Helium is the most electronegative element followed by Fluorine.

 

Here in the given options, Oxygen is the most electronegative element. Fluorine is followed by Oxygen, Chlorine and Nitrogen is the most electronegative elements list.

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Q:

The carbon tetrachloride molecule (CCl4) is

A) a nonpolar molecule with polar bonds B) a nonpolar molecule with nonpolar bonds
C) a polar molecule with polar bonds D) a polar molecule with nonploar bonds
 
Answer & Explanation Answer: A) a nonpolar molecule with polar bonds

Explanation:

The four bonds of carbon tetrachloride (CCl4) are polar, but the molecule is nonpolar because the bond polarity is cancelled by the symmetric tetrahedral shape. Hence, making the net dipole as zero and molecule as non-polar.

 

When other atoms substitute for some of the Cl atoms, the symmetry is broken and the molecule becomes polar.

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Q:

What is the bond order of O2?

A) 1.5 B) 2
C) 2.5 D) 1
 
Answer & Explanation Answer: B) 2

Explanation:

The number of bonds between a pair of atoms is called the bond order.

Bond orders can be calculated from Lewis structures, which are the heart of the valence-bond model. Oxygen, for example, has a bond order of two.

Structure

When there is more than one Lewis structure for a molecule, the bond order is an average of these structures. The bond order in sulfur dioxide, for example, is 1.5  the average of an S-O single bond in one Lewis structure and an S=O double bond in the other.

Structures

In molecular orbital theory, we calculate bond orders by assuming that two electrons in a bonding molecular orbital contribute one net bond and that two electrons in an antibonding molecular orbital cancel the effect of one bond. We can calculate the bond order in the O2 molecule by noting that there are eight valence electrons in bonding molecular orbitals and four valence electrons in antibonding molecular orbitals in the electron configuration of this molecule. Thus, the bond order is two.

Equation

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