Ultrasonic Vibrations:
(i) The Vibrations produced by sound waves with a frequency greater than 20 KHz are called ultrasonic vibrations.
(ii) Human ear cannot detect these waves.

i) Infrasonic.
ii) Application of Doppler effect.

On heating at 800^oC, aluminium burns very brightly forming it's oxide and nitride.
4AI + 3O₂ ➝ 2Al₂O₃ (Aluminium oxide)
2AI + N₂ ➝ 2AIN (Aluminium nitride)

Electronegativity of an element is the measure of the tendency of its atom to attract the shared pair of electrons towards itself in a covalent bond.

Atomic radius is of an atom defined as the distance between the centre of its nucleus and the outermost shell containing the valence electron.

Osmosis is the movement of solvent or water molecules from the region of higher concentration to the region of lower concentration through a semi-permeable membrane.

Hind brain is formed of three parts (1) cerebellum, (2) pons and (3) medulla oblongata.

RBCs are biconcave and disc - shaped.

Given: V = 331 ms^-1, λ = 0.20 m, n =?
V = n x λ
331 = n(0.20)
n = \(\frac{331}{0.20}\) = 1655 Hz

a) Definition:
Whenever there is a relative motion between a source and a listener, the frequency of the sound heard by the listener is different from the original frequency of sound emitted by the source. This is known as "Doppler effect'.
b) 

Bessemerisation The molten matte is transferred to Bessemer converter in order to obtain blister copper. Ferrous sulphide from matte is oxidized to ferrous oxide, which is removed as slag using silica.
2FeS+3O₂ ⟶ 2FeO+2SO₂ ↑

2 Cu₂S + 3O₂ ⟶ 2 Cu₂O + 2 SO₂

(i) The opening and closing of stomata is due to the change in turgidity of the guard cells.
(ii) When water enters into the guard cells, they become turgid and the stomata opens.
(iii) When the guard cells lose water, it becomes flaccid and the stomata closes.

(i) Rust is the formation of scaling reddish brown hydrated ferric oxide on the surface of iron containing materials.
(ii) This compound is known as rust and the phenomenon of formation of rust in known as rusting.
(iii) \( 4 \mathrm{Fe}+3 \mathrm{O}_{2}+\mathrm{xH}_{2} \mathrm{O} \rightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O}\\ \quad \quad \quad \quad \quad\quad\text { (Rust hydrated ferric oxide) } \) 

(i) A - reddish brown metal - Copper
(ii) When copper is heated at < 1370 K in the presence of oxygen, copper forms black colour Copper (II) oxide (CuO).
(iii) \(2 \mathrm{Cu}+\mathrm{O}_{2} \stackrel{\text { below } 1370 \mathrm{~K}}{\longrightarrow} \underset{\text { (copper (Il)oxide-black) }}{2 \mathrm{CuO}}\)
(iv) When copper is heated at >1370 K in the presence of oxygen, copper forms red colour Cop-per (I) oxide \((\mathrm{Cu}_{2} \mathrm{O} )\)
(v) \(4 \mathrm{Cu}+\mathrm{O}_{2} \stackrel{\text { above } 1370 \mathrm{~K}}{\longrightarrow} \underset{\text { (copper-I-oxide-red) }}{2 \mathrm{Cu_2O}}\)
(vi) A - copper (Cu)
(vii) B - copper (II) oxide (CuO) - Black coloured
(viii) \(\mathbf{C} - copper-I-oxide \left(\mathrm{Cu}_{2} \mathbf{O}\right)-\operatorname{Red}\) coloured

 d = 4.54 km = 4500 m
 t = 3 s
v = ?
\(v=\cfrac { d }{ t } =\cfrac { 4500 }{ 3 } \)  
v = 1500 m/s

(i) When sound is reflected from a concave surface, the reflected waves are converged at a point.
(ii) So, the ceilings of the concrete wall is curved.

A neuron typically consists of three basic parts:
Cyton, Dendrites and Axon.
(i) Cyton:
(a) Cyton is also called cell body or perikaryon.
(b) It has a central nucleus with abundant cytoplasm called neuroplasm.
(c) The cytoplasm has large granular body called Nissl's granules and the other cell organelles like mitochondria, ribosomes, lysosomes, and endoplasmic recticulum.
(d) Neurons do not have the ability to divide, as there is no centriole
(e) Several neurofibrils are present. in the cytoplasm that help in transmission of nerve impulses to and from the cell body.
(ii) Dendrites:
(a) These are the numerous branched cytoplasmic processes that project from the surface of the cell body.
(b) They conduct nerve impulses towards the cyton.
(c) The branched projections increase the surface area for receiving the signals from other nerve cells.
(iii) Axon:
(a) The axon is a single, elongated, slender projection.
(b) The end of axon terminates as fine branches which terminate into knob like swellings called synaptic knob.
(c) The plasma membrane of axon is called axolemma, while the cytoplasm is called axoplasm.
(d) It carries impulses away from the cyton.
(e) The axons may be covered by a protective sheath called myelin sheath which is further covered by a layer of Schwann cells called neurilemma.
(f) Myelin sheath breaks at intervals by depressions called Nodes of Ranvier.
(g) The region between the nodes is called as internode.
(h) Myelin sheath acts as insulator and ensures rapid transmission of nerve impulses.
(iv) Synapse:
(a) A junction between synaptic knob of axon of one neuron and dendron of next neuron is called synaptic junction.

Definition: Transpiration is the evaporation of water from the aerial parts of the plant especially through stomata in the leaves.
Importance of Transpiration:
(i) Creates transpirational pull for transport of water.
(ii) Supplies water for photosynthesis.
(iii) Transports minerals from soil to all parts of the plant.
(iv) Cools the surface of the leaves by evaporation.
(v) Keeps the cells turgid; hence, maintains their shape.

Smelting (in a Blast Furnace):
(i) The charge consisting of roasted ore, coke and limestone in the ratio 8:4:1 is smelted in a blast furnace by introducing it through the hopper arrangement at the top.
(ii) There are three important regions in the furnace.

a) The Lower Region (Combustion Zone):
(i) The temperature is at \(1500^{\circ} \mathrm{C}\).
(ii) In this region, coke burns with oxygen to form CO₂ when the charge comes in contact with a hot blast of air.
(iii) It is an exothermic reaction since heat is liberated.
\(\mathbf{C}+\mathbf{O}_{2} \underset{\Delta}{\stackrel{1500^{\circ} \mathrm{C}}{\longrightarrow}} \mathrm{CO}_{2}+ Heat\)
b) The Middle Region (Fusion Zone):
(i) The temperature prevails at \(1000^{\circ} \mathrm{C}\).
(ii) In this region, CO₂ is reduced to CO.
\(\mathrm{CO}_{2}+\mathrm{C} \underset{\Delta}{\stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow}} 2 \mathrm{CO}-\text { Heat }\)
(iii) Limestone decomposes to calcium oxide and CO₂.
\(\mathrm{CaCO}_{3} \underset{\Delta}{\stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow}} \mathrm{CaO}+CO_2-\text { Heat }\)
(iv) These two reactions are endothermic due to absorption of heat.
(v) Calcium oxide combines with silica to form calcium silicate slag.
\(\mathrm{CaO}+\mathrm{SiO}_{2} \longrightarrow \mathrm{CaSiO}_{3}\)
c) The Upper Region (Reduction Zone):
(i) The temperature prevails at \(\mathbf{4 0 0 ^ { \circ } \mathrm { C } \text { . }}\)
(ii) In this region carbon monoxide reduces ferric oxide to form a fairly pure spongy iron.
\(\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \stackrel{400^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{Fe}+3 \mathrm{CO}_{2}\uparrow\)
(iii) The molten iron is collected at the bottom of the furnace after removing the slag.
(iv) The iron thus formed is called pig iron.
(v) It is remelted and cast into different molds.
(vi) This iron is called cast iron.

(i) Copper gets covered with a green layer of basic copper carbonate in the presence of CO₂ and moisture.
(ii) \(2 \mathrm{Cu}+\mathrm{O}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2}\)
(iii) Copper reacts with con. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) to from copper sulphate and SO₂.
(iv)  \(\mathrm{Cu}+2 \mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{CuSO}_{4}+\mathrm{SO}_{2} \uparrow+2 \mathrm{H}_{2} \mathrm{O}\)
(v)  So, A is-Copper (Cu)
\(\mathrm{B}\ is \ -\mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2}\) Basic copper carbonate.
\(\mathrm{C}\ is \ -\mathrm{CuSO}_{4}\) (copper sulphate)
\(\mathrm{D}\ is \ -\mathrm{SO}_{2}\) (Sulphur oxide)

Echo:
(i) An echo is the sound reproduced due to the reflection of the original sound from various rigid surfaces such as walls, ceilings, surfaces of mountains, etc.
a) Conditions necessary for hearing echo:
(i) The persistence of hearing for human ears is 0.1 second.
(ii) This means that you can hear two sound waves clearly, if the time interval between the two sounds is at least 0.1 s.
(iii) Thus, the minimum time gap between the original sound and an echo must be 0.1 s.
(iv) The above criterion can be satisfied only when the distance between the source of sound and the reflecting surface would satisfy the following equation:
\(\text { Velocity } =\frac{\text { distance travelled by sound }}{\text { time taken }}  \)
\(v =\frac{2 d}{t}  \)
\(d =\frac{v t}{2}\)
since, t = 0.1 second, then \(\mathrm{d}=\frac{331}{0.20}=\frac{\mathrm{v}}{20}\)
(v) Thus the minimum distance required to hear an echo is 1 / 20^th part of the magnitude of the velocity of sound in air.
(vi) If you consider the velocity of sound as 344 ms^-1, the minimum distance required to hear an echo is 17.2 m.
b) Applications of echo:
(i) The principle of echo is used in obstetric ultrasonography, which is used to create real-time visual images of the developing embryo or fetus in the mother's uterus.
(ii) This is a safe testing tool, as it does not use any harmful radiations.
c) Calculation of speed of sound:
(i) The sound pulse emitted by the source travels a total distance of 2d while travelling from the source to the wall and then back to the receiver.
(ii) The time taken for this has been observed to be 't'. Hence, the speed of sound wave is given by
\(\text { Speed of Sound }=\frac{\text { distance travelled }}{\text { time taken }}=\frac{2 \mathrm{d}}{\mathrm{t}}\)

a) Ultrasonic Vibrations:
(i) The Vibrations produced by sound waves with a frequency greater than 20 KHz are called ultrasonic vibrations.
(ii) Human ear cannot detect these waves.
b) Uses of Ultrasonic vibration:
(i) Ultrasonic devices are used to detect objects and measure distances.
(ii) Ultrasound imaging or sonography is often used in medicine.
(iii) In the non destructive testing of products and structures. Ultra sound is used to detect invisible flaws.
c) Certain creatures like mosquitoes, dogs, bats and dolphins can detect these waves.