Chemistry Mock Test- 2 - Class 9 MCQ

The process in which a gas turns into a liquid on cooling at a specific temperature is called condensation.

The latent heat of fusion is the amount of heat energy required to change a solid into a liquid at atmospheric pressure and at its melting point.

Magnesium has Atomic Number 12, It will be distributed in K, L, M shell in the following way:
K shell can accommodate a maximum of 2 electrons.
L shell can accommodate a maximum of 8 electrons and
M shell will accommodate 2 electrons.
So, the configuration becomes 2,8,2.

Kinetic Molecular Theory states that gas particles are in constant motion and exhibit perfectly elastic collisions.

Kinetic Molecular Theory can be used to explain both Charles’ and Boyle’s Laws.

The average kinetic energy of a collection of gas particles is directly proportional to absolute temperature only.

98.07848 g mol

The formula for sulfuric acid is H2SO4. The molar mass of sulfuric acid is 98.07848 g mol.

Carbon dioxide is a gas and has a weak intermolecular force of attraction between its molecules. It can be easily solidified and even liquified because it has a low melting point and low boiling point.

Atoms of different elements with different atomic numbers and the same mass number are known as isobars. 

Its equal to no.of protons but mass number =no.of protons +no.of neutrons

A gas is a substance with no definite volume and no definite shape. Solids and liquids have volumes that do not change easily. A gas, on the other hand, has a volume that changes to match the volume of its container. The molecules in a gas are very far apart compared with the molecules in a solid or a liquid.

The change of state from solid to liquid is known as Melting. This is a process in which a solid substance changes into a liquid on heating. Heat energy is required to break the bonds between molecules, allowing them to move around freely. This process is also known as fusion, and the amount of energy required is called the latent heat of fusion. In a phase diagram such as Figure 12.4.1, the melting point is the temperature at which a substance can transition from a solid to a liquid.

Naphthalene undergoes sublimation easily i.e., the change of state of naphthalene from solid to gas without the intervention of the liquid state. Thus, naphthalene balls keep on forming naphthalene vapours which disappear into the air with time without leaving any solid.

Air is a mixture of gases. Two main constituent of air are Oxygen (21%) and Nitrogen (78%). Other gases includes carbon dioxide, helium, water vapour etc.

Nano means very small so it is used as an unit for measuring very small things. The correct answer is option 'C'.

A mixture does not have a fixed melting point, boiling point etc. On the other hand, compounds have a a fixed melting point, boiling point.

The kinetic theory of matter can be used to explain how solids, liquids and gases are interchangeable as a result of increase or decrease in heat energy. When an object is heated the motion of the particles increases as the particles become more energetic.

An atomic mass unit is defined as a mass equal to one twelfth the mass of an atom of carbon 12. The mass of any isotope of any element is expressed in relation to the carbon 12 standard.

option ( b) is the correct✔ answer. 

 

Explanation:- first we have to calculate, the no. of molecules  and then we will compare them. To calculate the number of molecules, we multiply no. of moles with the Avagadro's number. 

• 0.5 *( 6.022 * 10^23) 

=  3.11 * 10^ 23

• 2* ( 6.022 * 10^23) 

=  12.044 * 10^ 23

• 3.35 * 10^19

• 0.05 * ( 6.022 * 10^23) 

= 0.3011 * 10^ 23

So, we can see, 4<1<3<2   is the correct✔ answer.

Answer:
The nucleous consists of protons and neutrons. Here is a detailed explanation of the components of the nucleous:
1. Protons:
- Protons are positively charged particles found in the nucleus of an atom.
- They have a mass of approximately 1 atomic mass unit (amu).
- The number of protons in an atom determines its atomic number, which defines the element.
2. Neutrons:
- Neutrons are neutral particles found in the nucleus of an atom.
- They have a mass similar to protons, approximately 1 amu.
- The number of neutrons in an atom can vary, resulting in different isotopes of an element.
3. Electrons:
- Electrons are negatively charged particles found in energy levels or shells outside the nucleus.
- They have a much smaller mass compared to protons and neutrons.
- The number of electrons in an atom is equal to the number of protons, ensuring overall neutrality.
Summary:
- The nucleus of an atom consists of protons and neutrons.
- Protons carry a positive charge and define the atomic number of an element.
- Neutrons are neutral particles and contribute to the mass of the atom.
- Electrons orbit around the nucleus in energy levels.

The correct option is A.
sodium is located in group 1, which means that it has 1
valence electron. This valence electron is located in sodium's third energy shell

Two laws are followed in this question.

The lightest particle among the options given is the electron. Here is a detailed explanation:
Electron:
- The electron is a subatomic particle with a negative electric charge.
- It is considered to be one of the fundamental particles of matter.
- It is symbolized by the letter "e" and has a charge of -1.
- Electrons are found outside the atomic nucleus in orbitals or energy levels.
- They have a very small mass compared to protons and neutrons.
- The mass of an electron is approximately 9.10938356 × 10^-31 kilograms.
Neutron:
- The neutron is a subatomic particle with no electric charge.
- It is also considered to be one of the fundamental particles of matter.
- Neutrons are found inside the atomic nucleus along with protons.
- They have a mass slightly larger than that of protons.
- The mass of a neutron is approximately 1.674927471 × 10^-27 kilograms.
Proton:
- The proton is a subatomic particle with a positive electric charge.
- It is also considered to be one of the fundamental particles of matter.
- Protons are found inside the atomic nucleus along with neutrons.
- They have a mass slightly smaller than that of neutrons.
- The mass of a proton is approximately 1.672621898 × 10^-27 kilograms.
Conclusion:
- Among the options given, the electron is the lightest particle.
- It has a smaller mass compared to protons and neutrons.
- Therefore, the correct answer is B: Electron.

The correct option is C.
The nucleus of an atom is made up of protons and neutrons (two types of baryons) joined by the nuclear force. These baryons are further made up of sub-atomic fundamental particles known as quarks joined by the strong interaction.

Correct Option is D.
Rutherford Model of an atom:
On the basis of Rutherford's experiment,
(1) An atom consist of positively charged, dense and very small nucleus containing protons and neutrons. The entire mass of an atom is concentrated in the nucleus.

(2) The nucleus is surrounded by negatively charged electrons. The electrons are revolving around the nucleus in circular paths at very high speed. These circular paths of the electrons are called orbits.

(3) An atom is electrically neutral because the number of protons and electrons is equal.

Most of the alpha particles passed through the gold foil undeflected because most of the space inside the atom is empty.

The valency of Calcium of 2+. Calcium has 2 electrons in its outermost shell, its electronic configuration being (2,8,8,2). In order to attain stability it loses 2 electrons to become stable according to the octet rule.

Water vapours at 100 degree Celsius has more energy than liquid water at 100 degree Celsius. This is due to the fact that on converting liquid into gas, latent heat of vaporisation is required. Thus the total energy of steam is the sum of latent heat and kinetic energy whereas liquid water consists of only kinetic energy.
Hence, we can say that molecules of steam have higher energy than the molecules of liquid water.