Question Discussion & Solution

Concept:

Latent heat: It is the amount of heat needed to change the state of a unit mass of any substance without changing its temperature.

i.e., we can say that heat needed to supply for changing its state will be directly proportional to the mass m of the substance.

∴Q ∝ m

i.e.,Q = mL

The SI unit of Latent heat is J/Kg and the CGS unit is Cal/g respectively.

Where,

m = mass of an object

L = Latent heat

Q = amount of heat needed to change the state of matter of mass m 

Explanation:

From the above explanation, we can see that Amount of heat needed to melt a unit mass of a substance is directly proportional to the amount of mass of an object since the Latent heat of a material is constant.

i.e., Q ∝ m ⇒ Q = mL

Thus the unit of latent heat can be expressed as \(L=\frac{Q}{m}\Rightarrow L=\frac{Joules}{kg}\)

The correct answer is Distance.

Key Points

• An odometer is a device that is used for measuring the distance traveled by a vehicle.
• The odometer is usually situated in the vehicle's dashboard.
• The word "odometer" is derived from two Greek words meaning path and measure.
• Odometer is also used by people who construct roads and survey lands.

Additional Information

402° - 302° = 100° in North-East direction

The correct answer is Tartaric acid.

• Tartaric acid is an organic acid that is white and crystalline.

Key Points

• It is found naturally in many fruits like grapes, bananas, tamarind, etc.
• This acid is added to foods as an antioxidant and to give its distinctive sour taste.
• Crystals and powders are prepared by a chemical process.
• It is also added to food for preservation.
• It is also a good antioxidant and is beneficial for kidneys.
• It helps to absorb minerals in the body.
• It is also helpful in controlling problems related to gases in the body.

Explanation:

• Pulses are considered to be nitrogen-fixing crops as they have root nodules onto which symbiotic nitrogen-fixing bacteria like Rhizobium get attached and fix atmospheric nitrogen
• Whereas, Cereals are the crops that demand a lot of nitrogen thus after harvest the soil becomes deficient in nitrogen, so to compensate for this deficiency a pulse crop is grown between two cereal crops
• This practice of growing different food crops alternatively in the same field is called Crop Rotation

Important Points 

Crop Rotation

• Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons
• It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant pests and weeds.
• Crop rotation involves planting a sequence of different kinds of crops in a location over a number of seasons.
• Rotating crops helps maintain or improve soil health and maintain or increase the productivity of the farm over time
• A diverse crop rotation gives the soil microbes different food sources, which ultimately makes soil healthier.