Here height =50 m

base= 200m

tanθ=height/base=50/200=1/4=tan14

so angle of depression=90-14=76

5*s=5s

• The region around the electric charge in which the stress or electric force act is called an electric field or electrostatic field. If the magnitude of charge is large, then it may create a huge stress around the region.
• The electric field is represented by the symbol E. The SI unit of the electric field is newton per coulomb which is equal to volts per meter.

1. Man-induced Deforestation: Deforestation is the cutting down of trees and plants to make way for any development activity. Mother nature taking out an entire forest is one thing, but man doing it for the use of crop cultivation, fuel, and other consumption, is another. Each day our forests are bulldozed for the prospect of farms and factories. Fuel used for wood and charcoal only adds to the polluted gases in the atmosphere. Our consumer commodities provided by forestry includes paper and lumber. The loss of our forests results in a chain reaction where too much carbon is released into the air, with not enough oxygen to combat it.
2. Fossil Fuels: Pollution whether it is vehicular, electrical or industrial is the main contributor to the global warming. Everyday billions of vehicles release various gases into the atmosphere. This causes earth to warm up and increase its average temperature. Electricity causes pollution in many ways. Over 75% of the electricity worldwide is produced by burning of fossil fuels. Many gases are sent into the air when <a href="https://www.conserve-energy-future.com/disadvantages_fossilfuels.php" rel="noopener" target="_blank">fossil fuels</a> are burnt of which main is the carbon dioxide gas.

Invar is a 36% nickel iron alloy which has the lowest thermal expansion among all metals and alloys in the range from room temperature up to approximately 230°C. The Invar alloy is ductile and easily weldable, and machinability is similar to austenitic stainless steel.

• The flow of electric charges across a cross-section of a conductor constitutes an electric current.
•  For example, a stream of electrons moving through a conducting wire constitutes an electric current.

The flow of electric charge is known as electric current. Electric current is carried by moving electrons through a conductor.
Electric Current(I) = Net charge(Q)/Time(t)
Or, I = Q/t
Where,I is electric current,Q is net charge and t is time in second.

A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series.

Environment : The physical, chemical and ‘ biological conditions of the region in which an organism lives is called its Environment. It includes air, light, soil, temperature, water and the presence or absence of other organisms, i.e., the conditions for development or growth.
Environment has three main components, viz :
(a) Physical surroundings [soil, air and water bodies]
(b) Living organisms [plants, animals, decomposers (bacteria and fungi)]
(c) Meteorological factors (or climatic factors) . [sunlight, temperature, rainfall, humidity, pressure and wind speed].

We produce Hydrogen Chloride in the laboratory by treating sodium chloride with concentrated sulphuric acid. We, then, heat this mixture up to 420K.

                              420K
NaCl    +  H2SO4        →       NaHSO4    +   HCl

We get Sodium bisulphate as a by-product. This is insoluble. Therefore, we further mix it with more sodium chloride. This mixture has to be further warmed to a higher temperature of around 823K. It gives dissolvable sodium sulfate and HCl gas.

                                 823K
NaHSO4    +    NaCl     →        Na2SO4     +    HCl

We dry this HCl by treating it with concentrated sulphuric acid. HCl is not dried over phosphorus pentoxide or brisk lime. This is because it reacts with both of these compounds.