Latent heat, energy absorbed or released by a substance during a change in its physical state (phase) that occurs without changing its temperature. The latent heat is normally expressed as the amount of heat (in units of joules or calories) per mole or unit mass of the substance undergoing a change of state. As ice melts or liquid water evaporates, the molecules change state — from a solid to a liquid, from a liquid to a gas, or from a solid directly to a gas. A total of 334 J of energy are required to melt 1 g of ice at 0°C, which is called the latent heat of melting.

1) Momentum is defined as the quantity of motion of the body. It is measured by mass×velocity, as momentum depends upon velocity, and it depends on the direction of the motion of the body as well. Momentum is a vector quantity since velocity is vector while mass is scalar.

Momentum = Mass X Velocity

p = mv

2.  There are five basic laws of chemical combination that govern the chemical combinations of elements:

1. Law of Conservation of Mass

In simple terms, this law states that matter can neither be created nor destroyed. In other words, the total mass, that is, the sum of the mass of reacting mixture and the products formed remains constant. 

2. Law of Definite Proportions

Joseph Proust, a French chemist stated that the proportion of elements by weight in a given compound will always remain exactly the same. 

3. Law of Multiple Proportions

This law states that if two elements combine to form more than one compound, the masses of these elements in the reaction are in the ratio of small whole numbers. This law was given by Dalton in the year 1803.

4.  Gay Lussac’s Law of Gaseous Volumes

In 1808, Gay Lussac gave this law based on his observations. This law states that when gases are produced or combine in a chemical reaction, they do so in a simple ratio by volume given that all the gases are at the same temperature and pressure. 

5. Avogadro’s Law

Avogadro proposed this law in the year 1811. It stated that under the same conditions of temperature and pressure, an equal volume of all the gases contains an equal number of molecules. This implies that 2 litres of hydrogen will have the same number of molecules as 2 litres of oxygen given that both the gases are at the same temperature and pressure.

White blood cells (Leucocytes)

Leucocytes are the colourless blood cells. They are colourless because it is devoid of haemoglobin. They are further classified as granulocytes and agranulocytes. WBCs mainly contribute to immunity and defence mechanism.

Lymphocytes are a type of white blood cell that function as part of the immune system. Their various functions allow them to properly respond to foreign invaders in the body. Some lymphocytes work alone, while others are able to coordinate with other cells.

We wear cotton clothes during summer as cotton absorbs sweat from the body, exposing to the atmosphere for easy evaporation. As we tend to sweat more during summer and cotton fabric absorbs sweat and help body to cool down. Cotton allows better air circulation which helps to absorb and removing body moisture caused by sweat via evaporation.

• Thomson’s model revealed that atom has spherical structure, with positive charge spread all over the sphere and electrons are embedded in it. Also there is equal number of positive and negative charge i.e. atom is electrically neutral.

• Ernest Rutherford carried out experiments by taking consideration in Thomson’s model and presented more accurate model i.e. Rutherford’s model. Rutherford bombarded ⍺ particles i.e. He²⁺ ions on gold foil. Gold foil has very thin thickness of about 1000 atoms thick. Observations of Rutherford’s experiment are
  • Most of ⍺ particles passes through gold foil
  • Some ⍺ particles get deflected with very small angles from their path
  • Very few i.e. 1/ 12000 were reflected back on same path

On basis of observations, Rutherford put forth conclusion

• Most ⍺ particles pass through gold foil, therefore, atom must have large empty space in it.
• Some ⍺ particles gets deflected, hence there is some strong dense opposition. ⍺ particle is positively charge. If ⍺ particle is deflected then, opposition must be having a positive charge.
• Very few ⍺ particles are deflected this shows that, positive and other mass of atom is in very small volume in the atom.
• Moreover, it was identified that radius of dense space is 10⁵ times smaller than size of atoms.

There is no comparison between diffusion and tissue. So mention some points may help you to understand Diffusion and tissue.

• Diffusion is the process of movement of molecules under a concentration gradient.
• It is an important process occurring in all living beings. Diffusion helps in the movement of substances in and out of the cells.
• The molecules move from a region of higher concentration to a region of lower concentration until the concentration becomes equal throughout.
• Liquid and gases undergo diffusion as the molecules are able to move randomly.

Tissue

• A group of cells that are similar in structure and work together to do a peculiar function is called tissue.
• Tissues provide structural strength, mechanical strength, show division of labour.
• The use of tissues in multicellular organisms is to provide structural and mechanical strength as well as to allow division of labour.

A quantity which has only magnitude but no direction is known as a scalar quantity.

Work is done only when a force produces motion.And it is the product of the force exerted on the the body and the distance moved by the body in the direction of force.
i.e. W =F.s

Work is actually the scalar product of force and displacement and hence is a scalar quantity.
W =F.s
i.e. W = Fs cos θ

where F is the force, s the displacement and θ the angle between force and displacement. According to the angle θ, work can be positive, negative, or zero.

Work is the outcome of the force and displacement caused by the body.

Force and displacement are vector quantities (they have both magnitude and direction) and the dot product of two vector quantites always gives a scalar quantity. So work has only magnitude but not direction.

Kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity.

Derivation: 

Let us consider an object of m which is at rest lying on a table.

Let A force F acts on the object which moves the object through a distance S.

The workdone=F×S

W=Fnet​×S-------(1)

Let the work done on the object causes a change in its velocity from u to V and let a be the acceleration.

From Third equation of motion:

V²−u²=2as

s=V²−u²/2a----------(2)

By Newton's Second law:

F=ma------(3)

From equation (1), (2) and (3)

W=ma×(V2−u2/2a)=(1/2)m(V2−u2)

As we assumed object at rest, u=0

W=(1/2)mV2

we know that the kinetic energy of a body moving with a certain velocity is equal to work done on the object to acquire that velocity from rest.

∴K.E=1/2mV2

 Mass of an object= the gravitational constant/ weight of the object.
The mass of an object whose weight in 196n is going to be 19.6 kg if the gravitational constant is taken to be 10g.
And it is 20 kg, in case the gravitational constant is taken to be 9.8 g.

An isotope of cobalt is used in the treatment of cancer.

An isotope of iodine is used to treatment of goiter.

Answer:
The cells formed by meristematic tissue take up a specific role and lose their ability to divide. As a result, they form a permanent tissue. This process of taking up a permanent shape, size and function is called differentiation.

A n s w e r :
The work done will be zero because a coolie carries a load make an angle of 90 degree wherever the 90 degree created the work done will be zero

In desert plants, rate of water loss gets reduced due to the presence of cuticle.

The epidermis of the desert plant has a thick layer of cutin that is called cuticle. It is a waxy layer present on the leaves whose primary function is to reduce the water loss from the plant.

Goblet cells derive their name from their goblet, cup-like appearance. They arise from pluripotent stem cells. The primary function of goblet cells is to secrete mucin and create a protective mucus layer. Regardless of fixation, goblet cells have a distinctly polarized morphology. Their nucleus is at the base of the cell, along with organelles such as mitochondria, endoplasmic reticulum and Golgi. The remainder of the cell is filled with membrane-bound secretory granules filled with mucus.

Sclerenchyma tissue found in the stem, root and many other parts of the plant, is made up of dead cells.

Average power is defined as the ratio of total work done by the body to the total time taken by the body. The unit of average power is kiloWatt hour. It is the average amount of work done or energy converted per unit of time. The average power is often simply called "power" when the context makes it clear. The instantaneous power is then the limiting value of the average power as the time interval Δt approaches zero.

The law of conservation of energy states that energy can neither be created nor be destroyed. Although, it may be transformed from one form to another. If you take all forms of energy into account, the total energy of an isolated system always remains constant. All the forms of energy follow the law of conservation of energy.  

While doing cooking, generally we add salt to vegetables ( contains water).
Adding salt, makes the concentration of salt higher in outside membrane of vegetables than in inside. ( more salt, less water)

As a result, due the process of OSMOSIS, water from vegetables comes outside making it softer and helps in faster cooking.

Plasmolysis is defined as the process of contraction or shrinkage of the protoplasm of a plant cell and is caused due to the loss of water in the cell. Plasmolysis is an example of the results of osmosis and rarely occurs in nature.

The word Plasmolysis was generally derived from a Latin and Greek word plasma – The mould and lusis meaning loosening.