April 24, 2024
Which of the following statements is correct about ultrasonic waves : 
1. They can destroy insects. 
2. They can clean clothes by removing dust. 
3. They can be used to treat diseases. 
4. They can control automatic doors.
  • (A) 1 and 2 are correct
  • (B) 1, 2 and 3 are correct
  • (C) 3 and 4 are correct
  • (D) All are correct
Two astronauts cannot hear each other on the moon's surface, because -
  • (A) Their ears have stopped working on the moon.
  • (B) No atmosphere on the moon.
  • (C) They wear special space suits on the moon.
  • (D) The sound travels much more slowly on moon.
Which of the following statements is correct 
1. The heart vibrates at infrasonic. 
2. The speed of sound is more in gas than in liquid and solid. 
3. Mach number is used to describe the speed of sound. 
4. Ultrasonic sound has frequency more than 20,000 Hz.
  • (A) 1, 2 and 3 are correct
  • (B) 2, 3 and 4 are correct
  • (C) 1, 3 and 4 are correct
  • (D) 1, 2 and 4 are correct
The technique used to transmit audio signals in television broadcast is -
  • (A) Amplitude modulation
  • (B) Pulse code modulation
  • (C) Frequency modulation
  • (D) Time dimension multiplication.
Which of the following is/are the example/examples of chemical change?
.1. Crystallization of sodium chloride
. 2. Melting of ice 
. 3. Souring of milk
. Select the correct answer using the code given below.
  • (A) 1 and 2 only
  • (B) 3 only
  • (C) 1, 2 and 3
  • (D) None  
Consider the following assertions in relation to photosynthesis:
1. Only oxygen is formed from the process of photosynthesis.
2. In addition to the leaves, the other green parts of plants also carry out photosynthesis.
Which of the above assertions is/are correct?
  • (A) 1 only
  • (B) 2 only
  • (C) Both 1 and 2
  • (D) Neither 1 nor 2
Cow's milk is slightly yellow in colour due to the presence of -
  • (A) Xanthophyll
  • (B) Vitamin B12
  • (C) Riboflavin
  • (D) Carotene  
The unit of heredity in our body is called
  • (A) Chromosome
  • (B) DNA
  • (C) Gene
  • (D) Nucleus
Which one of the following substances is used in the preservation of food stuff?
  • (A) Citric Acid
  • (B) Sodium Benzoate
  • (C) Potassium Chloride
  • (D) Sodium Chloride
The Technique chromatography is used to -
  • (A) Identify colour substances
  • (B) Determine the structure of substances
  • (C) Dry distillation of colouring substances
  • (D) Separate the substances from a mixture

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