Question

ANSWER THE FOLLOWING
DOWN
1. Solid form of carbon dioxide. (6 letters)
2. Rain containing mild mineral acids in it. (8 letters)
3. A combustible substance like LPG quickly catches fire on coming in contact with a
spark. (15 letters)
4. Contamination of air due to the addition of CO2 and CO gases. (10 letters)
5. Production of heat, light and sound while burning a combustible substance. (9 letters)
ACROSS
1. Least hot zone of a candle flame. (8 letters)
6. Respiratory disease caused by inhaling polluted air containing CO.(6 letters)
7. An element which burns spontaneously in air. (15 letters/9 letters)
8. The colour of LPG flame. (4 letters)
9. A gas which has high calorific value and filled in cylinders at high pressure for
domestic use. (3 letters)
10. Unburnt carbon particles produced due to incomplete combustion of wax vapours. (4 letters)
11. A combustible substance which produces a sufficient amount of heat on burning
without producing any harmful substance. (4 letters)
12. A gas having extremely high calorific value but not safe to use as fuel(8 letters)

Answer 1

$\red{\underline{\underline{\mathfrak{Answer :-}}}}$

1. Carbon dioxide, CO2, is usually a gas. It is exhaled by animals and humans and used by plants to produce oxygen. In solid form it is dry ice. Carbon dioxide is a chemical compound that consists of two oxygen atoms and one carbon atom.

2. Acid Rain is a term used for rain with a pH of less than 5.6. ... This mild acidity is due to dissolution of CO2, that forms carbonic acid and due to the presence of chemicals produced by lightening and volcanic activity. When the falling rain exhibits a pH value of less than 5.6, it is termed “acid rain”.

3. don't know

4. don't know

5. Explosion:

Explosion:In this type of combustion, all of a sudden reaction results into heat, light and sound. Moreover, large quantity of gas also gets released Example: When a fire cracker is ignited, a sudden reaction takes place with the evolution of heat, light and sound with the large amount of gas.

1. innermost

innermostThe yellow colour region which is the bright part of the flame is the middle zone. It is moderately hot and partial combustion of fuel takes place. The least hot region of the flame is present innermost. This inner zone is black due to the presence of unburnt wax vapours.

6. Air pollution is the cause and aggravating factor of many respiratory diseases like chronic obstructive pulmonary disease (COPD) (11,12), asthma (12,13), and lung cancer (14,15).

7. White phosphorus is highly reactive, and spontaneously ignites at about 30°C in moist air. It is usually stored under water, to prevent exposure to the air. It is also extremely toxic, even in very small quantities.

8. blue flame

blue flameThe LPG (propane) is a blue flame because complete combustion creates enough energy to excite and ionize the gas molecules in the flame. The exception is a gas fireplace having yellow or red flames, for a more realistic look.

9. LPG

LPGLPG is packed with energy. It is more energy-rich than other commonly used fuels such as natural gas, petrol, coal and diesel. With a technical term, it has a higher calorific value. This basically means that when you set LPG on fire, the flame temperature will be higher compared to the other fuels.

10. Candle burns with a yellow flame because of burning of low energy fuel in a low oxygen content. The incomplete combustion of wax produces small unburnt. Carbon particles which rise in flame, get heated and give yellow and luminous flame.

11. don't know

12. Although hydrogen has the highest calorific value, it is not used as a domestic fuel. It is because hydrogen is a highly combustible and it reacts explosively when it comes in contact with air. And hence as a result, storing of the hydrogen gas is difficult and is dangerous at the same time.

Question 3,4,11 I don't know