Tag: evs

Quizzes (439) Questions (4580)

Questions Related to evs

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

The mass of residue left after strongly heating 1.38 g of silver carbonate will be: 

  1. 1.16 g

  2. 1.33 g

  3. 2.66 g

  4. 1.08 g
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Ag _2CO _3\rightarrow Ag _2O+CO _2(g)$
I mole of $Ag _2CO _3$ (275.74) grams  on decomposition gives a mass residue of 231.73 grams of $Ag _2O$ remaning mass is liberated as $CO _2$ gas.
If 1.38 grams $Ag _2CO _3$ is hetaed it produces X grams of mass residue of  $Ag _2O$
$X=\frac{1.38\times 231.739}{275.745}=1.16$ grams
Hence option A is correct.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

At NTP, 10 litre of hydrogen sulphide gas reacted with 10 litre of sulphur dioxide gas. The volume of gas, after the reaction is complete, would be:

  1. 5 litre

  2. 10 litre

  3. 15 litre

  4. 20 litre
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$2H _2S+SO2\rightarrow 2H _2O+3S$

According to the equation $2\times 22.4 $ litre of  $H _2S$ gas reacts with $22.4$ litre of $SO _2$
So $5$ litre of $H _2S$ reacts with $10$ litre of $SO _2$
Hence option $A$ is correct.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

World's most problematic aquatic weed is ________________.

  1. Azolla

  2. Wolffia

  3. Elchhornia

  4. Trapa
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Eichhornia crassipes (water hyacinth) is the world's most problematic aquatic weed, also called "Terror of Bengal". Because of its very high rate of growth, it can cover the surface of whole water bodies, choke them and cause a threat to other aquatic life forms.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

Why you never see cattle or goats browsing on weed Calotropis?

  1. The plant produces highly poisonous tannin

  2. The plant produces quinine which is bitter in taste

  3. The plant produces cardiac glycosides

  4. The plant bears prickles
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Prey species have evolved various defenses to lessen the impact depredation. For pant, herbivores are the predators plants have evolved an astonishing verity of morphological and chemical defense against herbivores. Calotropis produces highly see any cattle or goat browsing on this plant. A wide variety of chemical substance that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.) are produced by them actually as defenses against grazers and browsers. So, the correct answer is 'The plant produces cardiac glycosides'.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

The exotic species, which when introduced in India became notorious weed, is

  1. Lantana camara

  2. Eichhornia crassipes

  3. Parthenium hysterophorus

  4. all of these.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Native to South America, Lantana camara was brought to India by the British as ornamental plants, possibly as long as 200 years ago. Forest officials in different parts of the country have watched helplessly as the invasive plant has spread, and efforts to contain it have gone largely in vain.

Eichhornia crassipes, commonly known as common water hyacinth, is an aquatic plant native to the Amazon basin, and is often a highly problematic invasive species outside its native range. It was introduced in Bengal in India because of its beautiful flowers and shapes of leaves, but turned out to be an invasive weed draining oxygen from the water bodies and resulted in death of many fish. Fish is a supplement food in Bengal, and because of the fish scarcity in Bengal caused by Eichhornia, the water hyacinth is also called "Terror of Bengal".
Parthenium hysterophorus is a species of flowering plant in the aster family, Asteraceae. It is native to the American tropics. Parthenium hysterophorus invades disturbed land, including roadsides. It infests pastures and farmland, causing often disastrous loss of yield, as reflected in common names such as famine weed. In some areas, heavy outbreaks have been ubiquitous, affecting livestock and crop production, and human health. As an invader it first appeared as a contaminant in imported wheat. Indian National Congress decided to import wheats from USA. The wheat was of inferior quality and was a controversial one. This weed is equally dangerous for all flora and fauna. It is highly dangerous for humans. It sucks the nutritious substances from soils, thus converting fertile ground into infertile ones.
So the correct option is 'all of these'.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

If pests and weeds are not controlled at proper time ______

  1. They can destruct the crops so much that most of the crop is lost

  2. They can destruct the crops so much that most of the crop is no effect

  3. They can destruct the crops so much that most of the crop is gain

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If weeds and pests are not managed, they compete for resources and damage the crop, leading to significant yield loss.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

In fact weeds _____

  1. Take up all the nutrients

  2. Reduce the growth of crop in various ways

  3. Above both options are correct

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Weeds reduce crop growth by consuming nutrients and by physically shading or crowding the crop, so both listed options are correct.

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

Removal of weeds from cultivated fields during the early stages _____

  1. Crop growth is essential for a good harvest.

  2. Just for spending time

  3. For new crop

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Removing weeds during early crop growth stages is essential for good harvest because weeds compete most aggressively with young crops. If weeds aren't removed early, they can stunt or kill crop plants before they establish. The sentence structure is awkward, but the meaning is that early weed removal benefits crop growth.