Eye defects due to the weakening of muscles in old age are corrected by _____.

1. 1. convex lenses
   2. concave lenses
   3. no treatment
   4. bifocal arrangements

Shortsightedness is corrected by the use of _____.

1. 1. concave lenses
   2. convex lenses
   3. plain glasses
   4. coloured glasses

Who was the first to speculate that Venus is completely covered with clouds?

1. 1. Copernicus
   2. Descartes
   3. Giordano Bruno
   4. Christian Huygens

Cardiograph is _____.

1. 1. an instrument for measuring movements of the heart
   2. a graph of heart beating
   3. a graph drawn between the heart-beating and other physiological activities
   4. All of the above

Titan, the largest moon in the solar system, is also the largest moon of _____.

1. 1. Saturn
   2. Jupiter
   3. Mars
   4. Uranus

Binocular is used to _____.

1. 1. see the stars
   2. see the distant object magnified
   3. see the sun
   4. All of the above

The instrument used for measuring the velocity and direction of wind is called _____.

1. 1. Barometer
   2. Potometer
   3. Anemometer
   4. None of these

The instrument used for measuring current strength is _____.

1. 1. Ammeter
   2. Voltameter
   3. Galvanometer
   4. All of the above

Supersonics or ultrasonics are _____.

1. 1. loud sound waves
   2. sound waves of frequency above the audible limits
   3. sound that can be heard even at very long distance
   4. None of the above

Actinometer is an instrument used for measuring _____.

1. 1. 1. activity of radioactive elements
      2. power of X-rays
      3. activity of lower animals
      4. direct heating power of the sun