Among the following, which is not the correct method for keeping the curd?
- A.Keeping in stainless steel vessel
- B.Keeping in copper vessel
- C.Keeping in plastic vessel
- D.Keeping in glass vessel
Correct answer
Explanation
The correct answer is B, keeping in copper vessel. Curd contains lactic acid, which reacts with copper and brass to form poisonous salts, so it should not be stored in them.
Curd is sour because bacteria such as Lactobacillus turn the lactose of milk into lactic acid. Acids attack reactive metals like copper and brass, forming copper compounds that spoil the taste and can cause food poisoning. That is why sour foods such as curd, pickles and tamarind are kept in vessels that do not react, and why brass and copper cooking pots were traditionally coated with tin (kalai).
A is wrong because stainless steel resists acids and is safe for curd.
C is wrong because food-grade plastic does not react with lactic acid.
D is wrong because glass is chemically inert and one of the best containers for curd.
Exam tip: curd has lactic acid; never store sour food in copper or brass vessels.
Practice Questions
View allA charged particle moves through a magnetic field B with a velocity v. Which one of the following statements is true for the force (F) experienced by the particle?
- A.F is maximum when v and B are parallel to each other.
- B.F is maximum when v and B are anti-parallel to each other.
- C.F is maximum when v and B are perpendicular to each other.
- D.The force F is independent of the angle between v and B.
Show answer
The magnetic force depends on the sine of the angle between velocity and field, and sin 90° is the largest value.
Read the full explanation →In Sun-Earth system, the Sun, the Earth and the Lagrange point L4 form :
- A.an isosceles triangle
- B.an equilateral triangle
- C.a straight line
- D.a scalene triangle
Show answer
L4 lies on Earth's orbit 60° ahead of the Earth, so it is as far from the Sun as from the Earth.
Read the full explanation →Which one of the following is the most characteristic property of an element?
- A.Density
- B.Boiling point
- C.Mass number
- D.Atomic number
Show answer
The number of protons in the nucleus defines an element, and no two elements share it. The atomic number (Z) is the number of protons in an atom's nucleus, and in a neutral atom it also equals the number of electrons, which decide chemical behaviour.
Read the full explanation →After using for some time, big transformers get heated up. This is due to the fact that
1. current produces heat in the transformers
2. hysteresis loss occurs in the transformers
3. liquid used for cooling gets heated
Select the correct answer using the code given below.
- A.1 only
- B.2 and 3 only
- C.1 and 2 only
- D.1, 2 and 3
Show answer
A transformer heats up because of energy lost inside it: heat from current in the windings and hysteresis loss in the iron core.
Read the full explanation →Statement I : A person may suffer from tuberculosis if she/he frequently visits crowded place.
Statement II : Bacteria of tuberculosis spread through droplets by sneezing or coughing.
- A.Both the statements are individually true and Statement II is the correct explanation of Statement I
- B.Both the statements are individually true but Statement II is not the correct explanation of Statement I
- C.Statement I is true but Statement II is false
- D.Statement I is false but Statement II is true
Show answer
Both statements are true, and the airborne spread of the TB bacterium is exactly why crowded places raise the risk.
Read the full explanation →