Question Discussion & Solution

Concept:

• Electroscope:
  • It is an early scientific instrument used to detect the presence of an electric charge on a body.
  • The first electroscope was a pivoted needle electroscope invented in the year 1600 by British Physicist William Gilbert.
  • It measures the charge that is dependent on the Coulomb electrostatic force that triggers the movement of the test charge.

Explanation:

• Seismograph:
  • It is an instrument that is used to detect and record earthquakes. generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not.
• Ammeter:
  • This is a meter that is used for measuring electric current. Current is the flow of electrons whose unit is ampere.
  • Hence the instrument which measures the flow of current in ampere is called as Ampere meter or ammeter.
  • the ideal ammeter has zero internal resistance.
• Voltmeter:
  • It is an instrument used for measuring the electric potential difference between two points in an electric circuit that is connected in parallel. 
  • It usually has high resistance so that it takes negligible current from the circuit.
•  An electroscope is a correct answer.

Milk is measured in litres.

Similarly, Rope is measured in Meters

The Correct Answer is Two.

 Key Points

• The water molecule is composed of two hydrogen atoms, each linked by a single chemical bond to an oxygen atom.
• Most hydrogen atoms have a nucleus consisting solely of a proton. 
• Water is a tasteless and odorless liquid at room temperature.
• It has the important ability to dissolve much other substance.

 Additional Information

• Two isotopic forms, deuterium and tritium, in which the atomic nuclei also contain one and two neutrons, respectively, are found to a small degree in water.
• Deuterium oxide (D2O) is called heavy water
• It is used as a neutron moderator in some nuclear reactors.

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.

A cage is meant to keep something surrounded, so enclosure is the essential element. A prisoner (choice b) or an animal (choice c) are two things that may be kept in cages, among many other things. A zoo (choice d) is only one place that has cages.