Science M.C.Q-[Che-1M]

3. It has same number of protons & electrons

Explanation:

Atoms is electrically neutral as the number of protons is equal to the number of electrons.

Therefore the negative and positive charge cancels out.

2. Dalton

Explanation:

Dalton Atomic theory postulates-

All matter is made up of atoms and atoms are indestructible cannot be created or destroyed so the total mass of reactants remains equal to the total mass of products.

3. Proust

Explanation:

The law of constant proportion was given by Joseph L. Proust.

1. Democritus

Explanation:

Democritus postulated that matter is made up of very tiny particles i.e atom. In approximately 430 B.C.

Democritus coined the term atoms, which means “un-cuttable” or “the smallest indivisible particle of matter.

They are homogeneous, contain no void and no interstices, and are in perpetual motion moving equally in all directions.

2. Antoine Lavoisier

3. Dalton

Explanation:

Dalton believed matter to be made up of tiny indivisible particles called atoms. 

Both Thomson and Rutherford considered the presence of charged species in an atom and did not believe in the indivisibility of atom.

3. Proust

Explanation:

The concept of atomic mass was proposed by William Prout.

Early atomic mass theory was proposed by the English chemist William Prout in a series of published papers in 1815 and 1816.

Known as Prout's Law, Prout suggested that the known elements had atomic weights that were whole number multiples of the atomic mass of hydrogen.

1. Electrons

4. Trapping the gas and measuring its mass.

Explanation:

As gas can escape after reaction so after its release trap the gas and finding its mass so that it will be in accordance with the law of conservation of mass.

3. 2 moles of CaCO₃ would weigh the highest.

Explanation:

1. Mass of 1 mole of sucrose (12 × 12) + (1 × 22)+ (16 ×11) = 342g

2. Mass of 1 mole of CO₂ = 12 + (16 × 2) = 44g. Mass of 2 moles of CO₂ = 44 × 2 = 88g
3. Mass of 1 mole of CaCO₃ = 40 + 12 + (16 × 3) = 100g

4. Mass of 1 mole of H₂0 = 2 + 16 = 18g

4. Zn

Explanation:

K, Na, Cu is derived from Latin names namely Kalium, Natrium, and Cuprum.

The symbol of Zinc is not taken from Latin names.

4. Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

1. Atoms are not able to exist independently.

4. Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

Explanation:

The molecules and ions aggregate together in large number to form the matter. We cannot see the individual molecules/ ions with our eyes, only we can see the various substances which are a big collection of molecules/ ions. Atoms of only inert gases can exist independently, i.e. as single atoms. Rest of the statements about an atom are true.

4. An atom and its ion have an unequal number of protons.

Explanation:

An atom and its ion have an equal number of protons.

Thus, for example, a chlorine atom and chloride ions have an equal number of protons. 

When the chlorine atom is converted into a chloride ion, there is no change in the composition of the nucleus. 

A chlorine atom has one electron less than a chloride ion.

Chlorine atom gains one electron to form chloride ion.

4. All of the above

Explanation:

Mole is used to find number of particles.

1 mole is equal to Avogadro number of atoms/ molecules.

It is chemist's counting unit.

2. BiPO₄

2. Na₃N

Explanation:

The correct chemical formula among the listed chemicals is of Na₃N.

2. BiPO₄

Explanation:

The compound among these that has the correct chemical formula is BiPO₄.

4. All of these

2. 12g of magnesium and 6g of carbon.

Explanation:

12g of magnesium and 6g of carbon will have a mole ratio of 1 : 1

2. Compounds

Explanation: 

The Law of constant proportion is the rule where elements combine in a fixed proportion by mass.

Thus compounds are the kind that is formed from a fixed proportion of elements.

For example, Water →H₂​O is obtained from any source of water like a river, lake, pond. Here the ratio of H and O will be always 2 : 1.

1. Sulphur.

Explanation:

Octa atomic species are those which are made up of eight atoms.

For example, sulphur molecule is an octa atomic molecule made up of eight atoms of sulphur and is denoted by S₈.

4. Copper - Co

4. None of above.

4. Atoms of different elements can have same mass.

Explanation:

Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.

4. Atoms of a single element can have different masses

Explanation:

Postulates of Dalton's atomic theory:

All matter consists of indivisible particles called atoms.

Atoms of the same elements are similar in shape and mass but differ from the atoms of other elements.

Atoms cannot be created or destroyed.

Atoms of different elements may combine with each other in fixed, simple, whole-number ratios to form elements and compounds.

The atom is the smallest unit of matter that can take part in a chemical reaction.

'Atoms of a single element can have different masses' is not present in postulates of Dalton's atomic theory.

It is in fact a limitation of Dalton's atomic theory

1. O

Explanation:

A molecule may be homonuclear, that is, it consists of atoms of a single chemical element, as with oxygen (O_2​ or N_2​), or, it may be heteronuclear, a chemical compound composed of more than one element, as with water (H_2​O or CO₂​).

Out of all the options, O  represents a single oxygen atom and not a molecule.

3. Atoms of all elements are alike, including their masses.

Explanation: 

The main assumptions or postulates of Dalton are:

All matter consists of indivisible particles called atoms.

Atoms of the same element are similar in shape and mass but differ from the atoms of other elements.

Atoms cannot be created or destroyed.

Atoms of different elements may combine in a fixed, simple, whole number ratio to form compound atoms.

Atoms of the same element can combine in more than one ratio to form two or more compounds.

Atoms are the smallest unit of matter that can take part in a chemical reaction.

4. 22400ml of NH₃ gas at STP

Explanation:

0.1mol of CO₂ gas has smallest number of molecules .

4. Neon.

Explanation:

Neon’s molecular mass is equivalent to its atomic mass.

2. Phosphorus

Explanation:

The symbol,  P, represents the element Phosphorus.

Sulphur is represented by the symbol  S.

Oxygen is represented by the symbol O.

Hydrogen is represented by the symbol H.

3. 1g H₂

4. 2, 8, 2

Explanation:

The electronic configuration of 2, 8, 2 will lose two electrons to become positively charged ion i.e cation.

1. 2, 6

Explanation:

The electronic configuration of 2,6 will accept two electrons to become an anion or negatively charged ion.

For all the other configurations, losing electrons would lead to a more stable state and would form cations instead.

4. 17

2. ​​​​​​Law of conservation of mass

Explanation:

Antoine-Laurent Lavoisier established the law of conservation of mass. 

It states that "mass can neither be created nor be destroyed in a chemical reaction."

3. Law of conservation of energy

Explanation:

The Law of conservation of energy is not one of the laws of chemical combinations.

4. Maharishi Kanad

4. Hydrochloric acid

Explanation:

Molar mass of Hydrochloric acid = 1 × atomic mass of H + 1 × atomic mass of Cl

= 1 × (1) + 1 × (35.5)
= 36.5u

3. White precipitate is formed.

2. 36

2. Quantity

Explanation:

The law of conservation of mass states: Mass can neither be created nor destroyed in a chemical reaction.

According to this law mass of an isolated system will remain constant over time.

This means when mass is enclosed in a system and no transfer of material and energy is allowed in or out, its quantity will never change.

1. Increases

1. Water

Explanation:

When hydrogen burns in oxygen, water is produced.

The reaction is as follow:

2H₂​ + O₂​ → 2H₂​O

2. 320g

Explanation:

5 moles of SO² would be approximately 320.325g. 1 mole of SO2 has a mass of 64.065g (approx). This is calculated using the relative masses of sulfur (32.065g/mol) and oxygen (16.00g/mol).

2. 35.5

Explanation:

Chlorine is a chemical element with the symbol Cl and atomic number 17.

The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them.

The atomic mass (u) of Chlorine is 35.5u.