2
Q:

# A mixture of ethyl alcohol  and water can be seperated  by

 A) evaporation B) sublimation C) using a seperating funnel D) fractional distillation

Explanation:

Fractional distillation is the process of seperation of a mixture of two or more liquids into the different fractions, which differ fairly widely in their boiling points. The liquid with a lower boiling point will be vaporized first and hence would be the distillate (first fraction). Eg. Ethyl alcohol has a boiling point of $78.{1}^{0}C$ and water ${100}^{0}C$. When a mixture of these two liquids is heated, alcohol vaporizes first and is collected separately as the distillate.

Subject: Chemistry
Q:

Chemical name of Gold?

 A) Argentinum B) Ferrus C) Aurum D) Selenium

Explanation:

The Chemical name of Gold is Aurum with symbol Au with atomic number 79 and a group 11 element. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal.

Chemically, gold is a transition metal.

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0 27
Q:

What is the oxidation number of sulfur in H2S?

 A) 2 B) -2 C) 1 D) -1

Explanation:

The sum of the oxidation numbers in a compound must equal zero. In the compound hydrogen sulfide, H2S, the two hydrogen atoms have an oxidation number of +1, for a total of +2.

Therefore, the oxidation number of sulfur in the compound is -2, and the sum of the oxidation numbers is 0.

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0 26
Q:

Iron rusting, chemical or physical change

 A) Chemical B) Physical C) Both A & B D) None of the above

Explanation:

In rusting the Iron ore make a chemical reaction with the oxygen in the presence of water and environmental or atmospheric moisture to produce an Iron oxide. Iron oxide is otherwise called as rust.

The rusting of iron is a chemical change because it is two substances reacting together to make a new substance.

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0 26
Q:

When combining with nonmetallic atoms, metallic atoms generally will

 A) Lose electrons and forms cations B) Gain electrons and forms anions C) Lose electrons and forms anions D) Gain electrons and forms cations

Explanation:

When combining with nonmetallic atoms, metallic atoms generally will Lose electrons and forms cations.

As the ionization energy of te metals are very low, so they can easily lose electrons and form positively charged ion called cations.

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0 46
Q:

Which statement is true of all atoms that are anions?

 A) The atom has fewer protons than does a neutral atom of the same element. B) The atom has more protons than electrons. C) The atom has more neutrons than protons. D) The atom has more electrons than protons.

Answer & Explanation Answer: D) The atom has more electrons than protons.

Explanation:

Anions are atoms or radicals (groups of atoms), that have gained electrons. Since they now have more electrons than protons, anions have a negative charge.

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0 38
Q:

The reactivity of an atom arises from

 A) the existence of unpaired electrons in the valence shell B) the energy differences between the electron shells C) the sum of the potential energies of all the electron shells D) the average distance of the outermost electron shell from the nucleus

Answer & Explanation Answer: A) the existence of unpaired electrons in the valence shell

Explanation:

When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.

Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

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0 61
Q:

Water is an example of?

 A) Element B) Molecule C) Compound D) Both B & C

Explanation:

Why Water Is Not an Element :

An element is a substance consisting of only one type of atom. Water consists of two types of atoms: hydrogen and oxygen.

water is both a molecule and a compound :

A compound forms whenever two or more atoms form chemical bonds with each other. The chemical formula for water is H2O, which means each molecule of water consists of one oxygen atom chemically bonded to two hydrogen atoms.

Thus, water is a compound.

It's also a molecule, which is any chemical species formed by two or more atoms chemically bonded to each other. The terms molecule and compound mean the same thing and can be used interchangeably.

Hence, water is both a molecule and a compound.

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0 100
Q:

Milk is an example of a

 A) Emulsion B) Solution C) Gel D) Suspension

Explanation:

Milk is an emulsion of oil in water (o/w).

Emulsion: A suspension of droplets of one liquid in another.

Constituents of milk :

The principal constituents of milk are water, fat, proteins, lactose (milk sugar) and minerals (salts). Milk also contains trace amounts of other substances such as pigments, enzymes, vitamins, phospholipids (substances with fatlike properties), and gases.