Wednesday, 24 October 2018

Water Pollution

Water Pollution


What is Pollution
Explained below is Water pollution which is kind of hazardous pollution. 


Water Pollution 

When water body is polluted, it threatens aquatic life on both fresh water bodies, oceans and seas.

Fresh water is polluted through the discharge of sewage and other waste substances from farms and also from industries.

Marine pollution is mostly caused by oil spillage, industrial waste, agricultural waste and other waste matter.

Effects of Water pollution

1) Sewage can contaminate drinking water.
2) Aquatic life will be affected.
3) Gammalin 20 has a killing effect of fishes.
4) It makes water unfit for recreational purposes and swimming.
5) Odours emanating can be embarrassing.
6) Epidemic diseases like cholera and diarrhea are very common.
7) Excessive use of pesticides and fertilizers can drain into the rivers to kill aquatic animals.
8) Thermal heat from refineries, steel mills, breweries, causes increase in temperature of rivers.
9) Eutrophication causes depletion of oxygen in water.

Tuesday, 23 October 2018

GMAT WORD PROBLEM

Take the GMAT WORD PROBLEMS Past Questions Test 


Solutions 

1$1,200

The family pays $800 per year for the plan, plus (100 percent minus 80 percent) or 20 percent of the first $1,000 in medical expenses, while the insurance company pays 80 percent of the first $1,000, or $800. It must pay an additional $200 to match what the family pays out. Since the $200 comes after the first $1,000 in expenses, it must represent 100 percent of additional expenses. Therefore, there must have been $1,000 plus $200 or $1,200 in medical expenses altogether.

 2.  42

We're told that cheese, bologna, and peanut butter sandwiches are made in the ratio of 5 to 7 to 8. Every time they make 5 cheese sandwiches, they also have to make 7 bologna and 8 peanut butter. So there must be 5x cheese sandwiches (and we don't know what x is at this point), 7x bologna sandwiches, and 8x peanut butter. How many bologna sandwiches were made? Well, the number of bologna sandwiches must be a multiple of 7. But only choice D is a multiple of 7.
In other words:
5x + 7x + 8x = 120

 20x = 120
 x = 6
 7(6) = 42 .

3.   9

The key to solving this one is to focus on the quantity of water drained away, which we will call x. We're told that x liters of water are drained away, and x - 6 liters are left. So x (liters taken away) plus x - 6 (liters left) equals 12 (total liters in the sink).

Therefore 2x - 6 = 12, and x = 9.

4.  $11,800.

Since 25 products sell at an average of $1,200, to buy one of each we'd have to spend 25 x $1,200 = $30,000. We want to find the greatest possible selling price of the most expensive product. The way to maximize this price is to minimize the prices of the other 24 products. Ten of these products sell for less than $1,000, but all sell for at least $420. This means that we can have 10 sell at $420. That leaves 14 more that sell for $1,000 or more. So, in order to minimize the prices of these 14 products, we would want to price each at $1,000. That means that, out of the $30,000 total that it will take to purchase one of each item, only 10($420) + 14($1,000) = $18,200 is needed in order to purchase the 24 cheapest items.

The greatest selling price of the most expensive item can thus be calculated as $30,000 - $18,200 = $11,800.

5.   3

The quickest solution is to pick numbers for n and m. Since n = 1 and m = 1 would amount to 7 points, and since we want to minimize the difference between n and m, and since 50/7 is just a bit more than 7, we'll start with values near 7.

The key is to discover what values for n, when multiplied by 2 points, will leave a multiple of 5 as the remaining points. The solution turns out to be 5 for n (10 points), which allows for 8 for m (40 points). That's a total of 50 points, and the positive difference between the two values is only 3.



Friday, 5 October 2018

Air pollution



Read the previous post on Pollution to get the concept. 

What is Air Pollution?

This is mainly caused by air-borne particles, such as; smoke, carbon dioxide, Sulphur dioxide, carbon monoxide, Oxides of Nitrogen, hydrocarbons, chloro fluorocarbon, hydrogen Sulphide and dust.

Effects of Air Pollution 
1) It can cause bronchitis.
2) It can cause Silicosis.
3) It can lead to eye and nose irritation.
4) It can poison the blood forming carboxyl haemoglobin.
5) It can green house effect.
6) Dust and smoke can cause asthma.
7) Lead poison can affect children's IQ.
8) Nitrogen oxide irritates the lungs.

Control of Air Pollution 
1) Industries should be sited away from residential areas.
2) Passing of wastes through filters and absorbents should be put to practice.
3) The use of lead free fuels is important.
4) Avoid driving cars that are not well maintained.

Tuesday, 11 September 2018

Chemistry: Molar Mass, Examples and Solutions



Molar mass

The formula mass or molar mass of a compound is the mass of the correctly written formula or one molecule of the compound, obtained by adding together the appropriate relative atomic masses of the atoms of the elements present in the molecule.

Sunday, 2 September 2018