Question

4.

Answer 1

Explanation:

• For 4:

A compound is defined as the substance which is formed from the combination of two or more elements in a fixed ratio. They show different properties than the element from which they are formed from. For Example: $CO_2$ shows different properties than carbon and oxygen atoms.

Hence, the correct statement is entirely new properties than the elements that composes it.

• For 5:

Compounds are formed when two or more atoms of different elements combine chemically. So, the compounds can be separated by any chemical means only.

Hence, the correct answer is chemical means.

• For 6:

Atomic number for an element is defined as the number of protons or number of electrons.

Electrons cannot be used to characterize an element.

Atoms that have same number of protons belong to same element and atoms which have different number of protons belong to different element.

Thus, the correct answer is protons.

• For 7:

An ionic bond is formed when complete transfer of electrons takes place from one atom to another. An atom which donates electrons is considered as an electronegative atom and the one which accepts electrons is considered as an electropositive element.

The compound formed is an ionic compound. This compound is usually formed when a metal combines with a non-metal.

A covalent bond is formed when sharing of electrons takes place between two atoms combining. This compound is formed when two non-metals combine.

Hence, the correct answer is ionic compound.

• For 8:

For a given compound FeS. The chemical name for this compound is ferrous sulfide.

This compound is formed from the combination of iron and sulfur. Iron belongs to Group 8 and is considered as a metal. Sulfur belongs to Group 16 and is considered as a non-metal.

These two atoms will combine to form an ionic compound.

Thus, the correct answer is ionic compound.

• For 9:

Weight is defined as the amount of gravitational pull that acts on an object having mass 'm'. It is expressed by an equation:

$W=mg$

where,

W = weight

m = mass of the object

g = acceleration due to gravity

An object will have same mass on every planet but will have different weight due to the change in strength of gravity.

Hence, the correct answer is Weight.

• For 10:

Calcium is the 20th element of the periodic table. The number of electrons this element has are 20.

The electronic configuration for this element = $1s^2s^22p^63s^23p^64s^2$

Number of electrons that are present in third energy level (n = 3) for this element are 8.

Hence, the correct answer is 8.

Answer 2

Answer 4) Option B) entirely new properties than the elements that composes it

Explanation :

A compound takes on entirely new properties from the elements that it is composed from. There are many chemical bonds broken and made for new chemical compound to be formed which changes the properties of the new compound than the elements.

Answer 5) Option B)Chemical means

Explanation :

A compound can be separated by chemical means only unlike mixtures which can be separated by physical means.  Compound has to be chemically destroyed into elements.

Answer 6) Option C) protons.

Explanation :

All atoms of the same element must have the same number of protons but can differ in number of neutrons.  In the process of covalent compounds they share electron and in ionic form they lose electrons. So, electrons are not always same for the same element.

Answer 7) Option B)Ionic compound

Explanation :

When metal forms bond with a nonmetal it usually forms an ionic compound.  Ionic bonds are formed when metal loses an electron and a non metal gains that electron.

Answer 8) Option D) Ionic compound

Explanation :

The compound FeS is an example of an ionic compound as Fe is the metal and S is a non metal.

Answer 9) Option C) Weight

Explanation :

Weight is influenced by the strength of gravity rest other factors remains unaffected by the gravity.

Answer 10) Option A) 8  

Explanation :

Calcium atom has 20 electrons in its atom.

Which is further divided into 4 different energy levels 2,8,8,2.

Where 1st has 2 electrons, 2nd has 8 electrons and 3rd has 8 electrons and 4th also has 2 electrons.