Which of the following sound frequencies can be heard by a woman having a normal hearing range?
A. 25000 Hz
B. 15 kHz
C. 40000 Hz
D. 25 Hz
(a) A and B (b) B and C (c) B and D (d) only D
(c) B and D
Which of the sounds having the following frequencies can be heard by the human beings and which cannot?
(a) 6 Hz (b) 5000 Hz (c) 10000 Hz (di) 35000 Hz (e) 18 kHz
Which of the following can be electroplated with chromium ? A. Bakelite B. Graphite C. Steel D. Teflon
(a) A and B (b) B and C (c) only C (d) B and D
Complete the following sentences :
(a) An average person can hear sound of frequencies in the range ___ to ___.
(b) Ultrasound is of frequency ___ .
(c) Infrasonic sound is of frequency ___ .
(d) Bats can produce and hear ___ sound.
(e) Elephants produce ___ sound.
Which of the following metals are produced by the electrolysis of their molten compounds ? A. Copper B. Silver C. Aluminium D. Sodium
(a) A and B (b) B and C (c) C and D (d) only D