Post-mid Term Tests

The phenomenon in which non-bodegradable chemical get accumulated at each tropic level of a food chain is called biological magnification.

Example: DDT shows biological magnification. It is an insecticide used to kill mosquitoes.

DDT gets accumulated in the successive trophic levels. Zooplankton, small nekton, larger fish etc., anyone who eats these fish also havehigher level of DDT than fish.

According to Newtons law of octaves when an elements are arranged in the order of increasing atomic mass, the properties of every eight element are repetitism of properties of that starting element.

Calcium is the element up to which the law of octaves was found to be applicable. After calcium every eight elements did not possess the same properties similar to that of the first.

The Water of crystallisation is the number of molecules of water present in the crysrtals of salts.

The baking soda has a chemical formula NaHCO₃

The washing soda has a chemical formula Na₂CO₃.10H₂O.

Thus, baking soda does not contain water of crystallisation.

Nuclear fusion reaction is responsible for the large energy production in the sun.

In the sun the fusion of two or more hydrogen nuclei fuse to form a helium nuclei. The chemical reaction of fusion reaction is given below:

²₁H +²₁H → ³₂He +¹₀n

Olfactory receptors are present in nose they detect the smell. They are sensitive to chemical stimuli.

Gustatory receptors are present in tongue they detect taste. They are sensitive to chemical stimuli.

• Solar heater and solar cell are the two activities in our daily life which use solar energy.

Solar cell:

• During the day, sunlight is converted to electricity and stored in the battery. At night, the battery supplies the electricity to the light until it is all used up or the photoreceptor shuts off the light as daylight reappears.

• Solar lights are easy and affordable and efficient way to power the street lights.

Solar water heater:

• Solar water heater uses solar thermal(heat) energy to increase the temperature of the components of the hearter thus, solar enegy heating water.

• Modern periodic table is the table in which the classification of elements ate done based on the modern periodic law, which states that all the physical and chemical properties of an element are the periodic functions of their increasing atomoc mumber.

• The cobalt and nickel are placed in the same slot with column of chlorine and bromine which have very different properties than these element and iron which resembles properties of cobalt and nickle is placed far away in Newland law of octaves. This problem has been resolved by the Modern periodic table by arranging the elements in the order of their atomic number without changing their own places.

• Atomic number of cobalt is 27 and nickel is 28.

The 3 R’s stands for reduce, reuse and recycle. The 3Rs help to conserve natural resources, save land, money and energy. The r’s are explained below:

i. Reduce: Avoid pointless purchases, so that unnecessary waste can be created. Things which are seldom used can be borrowed or shared with others. Buy bottles instead of cans and rechargeable batteries.

ii. Reuse: the articles which are normally consider as waste because sometimes it could be used for other purposes. Instead of throwing articles, reduce waste by using them for other purposes. For examples, Paper and envelopes can be used as scrap paper for making notes.

iii. Recycle: the waste products. To recycle something means that it will be transformed again into a raw material that can be shaped into a new item. By recycling we can conserve some amount of energy. Newspaper can be recycled to use it again. Pastics can be recycled to use again by maying fresh items.

The Ozone layer absorbs most of the Sun's harmful ultraviolet radiation.

These radiations are highly damaging to organisms. They an cause skin cancer in human being, damages eye, decrease crop yield, disturb global rainfall, etc.

Dialysis is a process applied for artificial removal of excess water, solutes and nitrogenous waste from the blood in those in those person whose kidneys are not able to to perform excretory functions in a natural way.

CFCs (Chlorofluorocarbons) are the group of chemical compounds which are mostly released from industries, refrigerators and air conditioners.

These gases are responsible for the depletion of ozone layer.

The metal m belongs to 13 th group mean the valency of the group 13 is 3

The valency for different groups are given below:

Valency of group 1 element is 1.

Valency of group 2 element is 2.

Valency of group 13 element is 3.

Valency of group 14 element is 4.

Valency of group 15 element is 3.

Valency of group 16 element is 2.

Valency of group 17 element is 1.

Valency of group 18 element is 0.

1 D is the power of a convex lens of 1m focal length.

Power of a lens is the ability of the lens to converge or diverge ray of light.

Power of lens, P=

Where,

F is the focal length of the lens

On solving for F, we get

Thus, the 1 D is the power of a covex lens of focal length 1m

The sodium chloride has a very high melting point of 801^oC is due to the fact the Na and Cl molecules in Na Cl are bounded together by strong electrostatic force of aattraction As for Na to react with Cl then electron ions by sodium is gained by the chlorine atom.

Na⁺ and Cl^- ions being charged attract each other and ionic bond is form between them.

Since the melting and boiling point of the ionic bonds are very high.

Thus NaCl being ionic compound has very high melting point.

Biogas is considered to be a boon to the farmers due to the following benefits:

• The animal waste and agriculture wastes such as dung, dry, leaves, dry plants,are used in the biogas plant to produce clean biogas which are used for domestic purposes such as in heating, cooking, for running tube-well engine and as an illuminant in a gas lantern.

• The slurry which is left in the bio gas plant can be used in the fields as manure to increase the fertility of the soil.

This saves the farmer a lot of money which should have been otherwise spent on chemical fertilizers.

Thus, the biogas plants are considered a boon to farmers.

Coal, petroleum and natural gas are examples of fossil fuels. They take millions of year to form.

The various need for alternative source of energy is given below:

1. The over-extraction of fossil fuels is slowly depleting from the earth.

2. Burning of fossil fuel cause air pollution So, the consumption of fossil fuels in should be limited and must give more focus on alternative source of enrgy.

Alternative energy generally refers to any group of non-traditional fuel sources that does not burn fossil fuels or use up any type of natural resources which will result in damage or harm to the environment.

Examples are wind energy, hydroelectric energy, nuclear energy, and solar energy.

The technical terim for the graphical representation of the trophic structure in a food chain is Food web.

A food web is the natural interconnection of foos chains and a graphical representation of different food chains, which correlate at various level operating in an ecosystem.

The covalent bond is present in F₂ generation.

It has 7 electrons in the outer most shell and thus require 1 more electron to fulfil its outermost shell, This is achieved by sharing 1 electron with another F-atom, forming a chlorine diatomic molecule(F₂)

Methane gas is formed by decomposing plants and animal matter in marshy areas

The element wit symbol B is Boron.

The element with symbol Si is Silicon.

The element with symbol Ge is Germanium.

Many farmers grow only one type of crop say paddy in the same field year after year.This practice is called monoculture crop.

Drawbacks of monoculture are:

a. When a farmer grows only one type of crop, there is depletion of same type of nutrient from the soil. The soil become weak and unable to support healthy plant growth

b. Monocropping also creates the spread of pests and diseases, which must be treated with more chemicals.

The Calcium Sulphate Hemihydrate (CaSO₄.1/2 H₂O)is formed as the product of heating of gypsum at 373K.

The chemical formula for gypsum is CaSO₄.2 H₂O

The above chemical reaction can be given as

The cord of electric resistance is made of copper or aluminium which are good conductors of electricity. Thus possess negligible amount to resistivity while the heating element is made of nichrome or tungsten wire which has very resistivity.

Since the Heat, H=I² RT

Thus, more the resistance more the heat generated by the material.

Hence, the cord of an electric heater due to very negligible resistance does not glow while the element due to its high resistance glow.

“Sustainable development is a type of development which meets the needs of the present generation, without compromising the needs of future generations to meet their needs."

sustainable development is about finding better ways of doing things, both for the future and the present. We might need to change the way we work and live now, but this doesn't mean our quality of life will be reduced.

As tha atomic radii decreases along a period.

Thus, the elements will be arranged in the following increasing order

F<N<Be<Li

As the atomic size decrease when we across the period because the atomic number increases which attract the outermost electrons strongly due to which the size of elementsdecreases as we go frm left to right in a period.

The electrolytic Refining is used for the purification of metals of high reactivity.

The blue flame of burner indicates that the saturated hydrocarbon are burnt due to the their complete combustion.

(i) The element which has a three shell and three electrons in the outermost shell is Aluminium(Al)

The atomic number of Al is 13 which can be written as electronic configuration 2, 8, 3.

(ii) The second shell, l shell can have a maximum of 8 electrons. The third shell will have 4 electrons.

The required compound is Silicon(Si)-14

The electronic configuration of silicon is 2, 8, 4

(i) The covalent bond is formedbetween the X₇¹⁴ and Y₉¹⁸.

(ii) The element X₇¹⁴ is Nitrogen(N) which has electronic configuration 2,5

The element Y₉¹⁸ is Florine(F) which has electronic configuration is 2,7

Thus the Nitrogen molecule form covalent bond with three fluorine molecule.

The chemical Formula of the compound is NF₃.

The scattering of the light is the phenomenon responsible for making the path of the light visible.

When the light travel throught the atmosphere due to the presence of the air and dust molecule led light to scatter which led this particles to get reflected which fall in the path of the light which is responsible for making the path visible.

When a battery is connected to a closed circuit, charge flow in the circuit almost instantaneously because when electron flow in an conductor, the conductor have an electron drift velocity of 10^-4 m/s i.e the velocity of electron is =4 m/s. Thus it appears that the charges flow almost instantaneously when a battery is connected.

Coal, Oil and Gas are called "fossil fuels" because they have been formed from the remains of the plants and animals that had fossilized million years ago.

Fossil fuels are a non-renewable energy source since they take millions of years to form.

i. The mass of living material of the total number of organisms in at a particular trophic level.

ii. The biomass in each trophic level is always less than the trophic level below, because biomass is a measure of the amount of energys that is stored in living tissue at different trophic levels.

The anaerobic respiration occurs in our body when there is lack of oxygen during exercise.

human muscle cells undergo utilize anaerobic respiration when they lack sufficient oxygen or require a quick energy.

As a result of anaerobic respiration lactic acid is formed in the mucle cells which cause fatigue and muscle cramps after prolonged exercise.

The anaerobic respiration chemical reaction is given below:

Glucose →Pyruvate +Energy→ 2 latic acid + 2 ATP

The purpose of segregation of waste into blue and green dustbins is the part of wasete management system. The segregation of waste allow the waste material which acbe recycled is not dumped.

The blue bin is for plastic and metal waste.

The green bin is for biodegradable wastes.

The atomic size decreases along the period

The order is F< O< N< C <B

This due to increase in nuclear charge which tends to pull the valence electron closer to the nucleus and reduced the size of atom.

(i) The material used in galvanising of iron article is Zinc(Zn).

The metal Zn is found in the nature as ZnCO₃.

(ii) When the sodium is dropped to water.

a. Due to the reactivity of the sodium undergo exothermic reaction with water and heat is produced.

b. The H₂ gas is liberated which burns with a pop sound.

if the current is flowing in anticlock wise direction than the polarity on the end through which the current enter the solenoid will be South pole and on the end when the current leaves from the solenoid is North pole by the fleming’s right hand rule.

Hydropower plant capture the energy of falling water to generate electricity.

• A turbine converts the kinetic energy of falling water into mechanical energy.

• Then a generator converts the mechanical energy from the turbine into electrical energy.

It is a renewable resource of energy as energy is generated without the combustion of fossil fuels .

The bulb get fuse when operated at a higher potential because the filament of the bulb is made of tungsten which due to high resistance produce high amount of heat energy due to which it glows. When a higher potential is passed it leads to very high generation of heat which melts the tungsten element. Thus the circuit get opens and bulb get fused.

• In mendelian inheritance, one trait is dominant and other is recessive.

• Recessive trait cannot express itself in presence of dominant trait in First generation.

• In the first generation plants, recessessive gene (factor) is present in their genome but does not show its effect.

• When this first generation plants plants are crossed. The recessive gene separate form dominant gene during gamete formation.

• The recessive gene move to one gamete and dominant allele to another gamete.

• When male gamete containing recessive gene fuse with the recessive gene of female gamete for same trait in the second generation, the allele combination will become fully recessive and make the phenotype dwarf for the plant height character.

• Recessive trait appears only in in its homozygous condition. Threfore, dwarf trait reappears during second generation in Mendel's Monohybrid cross.

• Crossing of First generation plants:

(tt) is the recessive plant reappers in the second generation.

The 3 R’s stands for reduce, reuse and recycle. It helps to cut down on the amount of waste we throw away. The 3Rs help to conserve natural resources, save land, money and energy. The people must use to dispose of waste properly to keep environment clean.We have to follow 3R’s. Let’s see how.

i. Reduce: Avoid pointless purchases, so that unnecessary waste can be created. Things which are seldom used can be borrowed or shared with others. Buy bottles instead of cans and rechargeable batteries.

ii. Reuse the articles which are normally consider as waste because sometimes it could be used for other purposes. Instead of throwing articles, reduce waste by using them for other purposes. For examples, Paper and envelopes can be used as scrap paper for making notes.

iii. Recycle the waste products. To recycle something means that it will be transformed again into a raw material that can be shaped into a new item. By recycling we can conserve some amount of energy. Newspaper can be recycled to use it again. Ppastics can be recycled to use again by maying fresh items.

The hind prain is responsible for all the involuntary movement.

It provides connection between spinal chord and rest of the brain.

The medulla oblongata is part of the Hind brain that controls these involuntary actions.

Different regions in the medulla oblongata control different cativities. Reflex centers are responsible for reflexes such as swallowing, vomiting, sneezing and coughing, the cardiac center is responsible for the regulation of the heart rate, the vasomotor center is responsible for the regulation of blood pressure and respiratory center is responsible for the breathing activity.

The harmful effects of using plastic are given below:

1. Plastic is a non-biodegradable substance and can't be broken into the simpler substances by the microorganisms.

2. Plastics are responsible for causing pollution by blocking the sewage lines

3. Plastic being non biodegradable cause the killing wildlife when ate by the animals

4. Plastic are made from fossil fuel hence on burning cause pollution.

Some of the alternatives to the plastic bags:

i. Use of jute bags instead of plastic bags for shopping.

ii. Uuse eco-friendly bags of recyclable matersis

iii. Use of disposable paper cups instead of plastic cups.

iv. Use of paper bags in shops.