Any chemical element that is an effective conductor of electricity and heat can be defined as a metal .

• imilarities between Evaporation and Boiling in terms of “ Transformation”

Both represent the transformation from the liquid to the gaseous phase

Structures that are formed when a substance is in liquid phase are broken down during both processes, transforming it into the gaseous phase.

• Similarities between Evaporation and Boiling in terms of “ Energy”

Both require energy Usually thermal, but other forms of energy can also be used in order to increase the kinetic energy of the molecules, in order to make them evaporate or boil.

• Similarities between Evaporation and Boiling in terms of “ External Conditions”

Both depend on external conditions Both the rate of evaporation and the critical boiling temperature highly depend on the surrounding air pressure, humidity and temperature of both the air and liquid.

Crystallisation is a process that separates a pure solid in the form of its crystals from a solution.
Crystallisation is better than evaporation because during Evaporation
• Some solids decompose or some, like sugar may get charred on heating to dryness.
• Some impurities may remain dissolved in the solution even after filtration which on evaporation contaminates the solid.

The thermometer used for measuring the temperature of human body is called clinical thermometer. The range of a clinical thermometer is from 35°C to 42°C.  A clinical thermometer cannot be used to measure high temperatures because it has been designed to measure only human body temperature which varies over a short range. If it is used to measure high temperatures, it will get damaged.

Weeding: Removal of weeds is called weeding. Weeding is usually done manually or by using a trowel. Weeds are also removed during ploughing. Weedicides are the chemicals which destroy weeds. 2, 4 – D is an example of weedicide. Weedicides are sprayed before flowering and seeding in weeds. A farmer needs to take precautions to prevent any harm from weedicide. The farmer needs to wear protective cloths and masks while spraying a weedicide.

Matters are made of tiny particles called atom. Atom is made of three particles; electron, proton and neutron. These particles are called fundamental particles of an atom or sub atomic particles.

Electron (e^– )- Electron is denoted by ‘e’ and is a negatively charged particle. The absolute charge over an electron is equal to 1.6x10^-19 of negative charge and is considered equal to – 1.

The relative mass of electron is 1/1836. Since the mass of an electron is very small, thus it is considered equal to 0. Electrons revolve round the nucleus of atoms.

Proton (p⁺) - Proton is denoted by ‘p’ and is positively charged particle. The absolute charge over proton is 1.6x10 ^-19 coulomb of positive charge and it is considered as unit positive charge. Thus absolute charge over a proton is equal to +1.

The absolute mass of a proton is equal to 1.6x10 ^-24 g and considered equal to 1 as it is equal to the mass of 1 hydrogen atom. Proton is present in the nucleus of atom.

Neutron (n) – Neutron is denoted by ‘n’ and is a neutral particle. The absolute mass of neutron is 1.6 x 10 ^-24 g. The relative mass of neutron is equal to 1. Neutron is presents in the nucleus of atom.

Cell division is the process by which a parent cell divides into two or more cells called daughter cells. Cell division usually occurs as part of a larger cell cycle. All cells reproduce by dividing into two, with each parental cell giving rise to two daughter cells every time they divide.  These newly formed daughter cells could themselves divide and grow, giving rise to a new cell population that is formed by the division and growth of a single parental cell and its descendant. In other words, such cycles of growth and division allow a single cell to form a structure consisting of millions of cells.

On the basis of Dalton’s Atomic Theory "The smallest particles of matter are called Atoms". All the matter in the universe is made of tiny particles called atoms.  There are 92 different kinds of atoms in nature. These 92 different atoms combine with one another to form different kinds of matter that we see in nature.

1. The Sun: The Sun heats up rocks during the day so that they expand. At night, these rocks cool down and contract. Since all parts of the rock do not expand and contract at the same rate, this results in the formation of cracks and ultimately the huge rocks break up into smaller pieces.
2. Water: Water could get into the cracks in the rocks formed due to uneven heating by the Sun. If this water freezes, it would cause the cracks to widen.
3. Living organisms: The lichen when growing on the surface of rocks they release certain substances that cause the rock surface to powder down and form a thin layer of soil.
4. Role of temperature: It is also play important role because fluctuations in temperature causes shrinking and swelling, frost action and general weathering in soils.
5. Topography (Relief, Altitude and Slope): It is considered as passive factor to modifying the effects of climate because it affects soil processes, soil distribution and the type of vegetation.

Diffusion in the ability of a gas to spread and occupy the whole available volume irrespective of other gases present in the container.
Thomas Graham in 1831 proposed the law of gaseous diffusion.
The law states that under similar conditions of temperature and pressure, the rates of diffusion of gases are inversely proportional to the square roots of their densities.
Mathematically Graham’s Law of Diffusion / Effusion
r ∝ 1 / √d
where r is the rate of diffusion and d is the density of the gas.

Three naturally existing isotopes of hydrogen are tritium, deuterium, and protium. Each isotope comprehends of unique properties. These isotopes are in common use till date. ⁴H to ⁷H are nuclei isotopes that are incorporated in the laboratory. One of the least stable isotopes of hydrogen is ⁷H and most stable isotope is ⁵H. The most stable radioisotope of hydrogen is tritium.

Collisions occur when one object strikes another. Problems involving collisions are usually solved using conservation of momentum and energy.

It is categorized into two types,

• Inelastic collision
• Elastic collision