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Showing 1351 to 1375 of 3046 questions (page 55 of 122).

1351. Detergents work better than soaps in hard water because their calcium and magnesium salts are

A. soluble B. insoluble C. volatile D. coloured E. acidic

1352. Urea is manufactured by reacting ammonia with

A. sulphur dioxide B. water C. carbon dioxide D. nitrogen E. carbon monoxide

1353. Eutrophication of a lake is caused mainly by

A. acid rain alone B. excess chlorine C. low temperature D. excess nutrients such as nitrates and phosphates E. high dissolved oxygen

1354. Dissolved oxygen in a river falls when organic pollution rises because

A. the water becomes acidic B. oxygen reacts with the pollutant directly only C. the temperature falls D. the pollutant displaces the oxygen physically E. micro-organisms consume oxygen while decomposing the organic matter

1355. Infrared spectroscopy is used chiefly to identify

A. isotopes B. functional groups C. molar mass D. optical activity E. crystal structure

1356. How many base units are defined in the International System of Units (SI)?

A. 9 B. 5 C. 8 D. 7 E. 6

1357. The dimensions of Planck's constant are the same as those of

A. angular momentum B. linear momentum C. power D. energy E. force

1358. A screw gauge has a pitch of 0.5 mm and 50 divisions on its circular scale. Its least count is

A. 0.001 mm B. 0.01 mm C. 0.05 mm D. 0.025 mm E. 0.5 mm

1359. Which of the following is a supplementary unit in SI?

A. mole B. kelvin C. newton D. joule E. radian

1360. The dimensional formula of pressure is

A. [ML-3T0] B. [ML-2T-2] C. [ML-1T-2] D. [ML2T-2] E. [MLT-2]

1361. If a quantity is measured as 4.0 cm with an absolute uncertainty of 0.1 cm, the percentage uncertainty is

A. 4% B. 0.4% C. 25% D. 2.5% E. 0.25%

1362. A dimensionally correct equation

A. is always physically correct B. may still be physically incorrect C. always contains a trigonometric term D. must be numerically correct E. cannot contain constants

1363. A unit vector perpendicular to the plane containing vectors A and B is given by

A. (A x B)/|A x B| B. (A.B)/|A||B| C. A + B D. A - B E. A.B

1364. The value of i . (j x k) is

A. j B. i C. -1 E. 1

1365. Two forces of 10 N each act on a body with an angle of 120 degrees between them. The magnitude of the resultant is

A. 17.3 N B. 14.1 N C. 0 N D. 20 N E. 10 N

1366. If A + B = A - B, then vector B must be

A. a null vector B. equal to A C. a unit vector D. parallel to A E. perpendicular to A

1367. Torque is defined as

A. r + F B. r . F C. r x F D. F x r E. F . r

1368. For a body in complete equilibrium, the number of independent conditions that must be satisfied is

A. 1 B. 5 C. 3 D. 2 E. 4

1369. The scalar product of two mutually perpendicular vectors is

A. maximum B. zero C. unity D. equal to their cross product E. negative

1370. A vector of magnitude 10 units makes an angle of 30 degrees with the x-axis. Its y-component is

A. 8.66 units B. 7.07 units C. 10 units D. 2.5 units E. 5 units

1371. Newton's second law of motion provides the definition of

A. action and reaction B. force C. inertia D. mass E. momentum

1372. The SI unit of impulse is equivalent to

A. J s B. kg m s-2 C. kg m s-1 D. N s-1 E. N m

1373. In a perfectly elastic collision, which quantities are conserved?

A. momentum and mass only B. momentum only C. kinetic energy only D. momentum and kinetic energy E. kinetic energy and mass only

1374. The maximum horizontal range of a projectile is obtained at a launch angle of

A. 45 degrees B. 75 degrees C. 30 degrees D. 60 degrees E. 90 degrees

1375. At the highest point of its trajectory, the velocity of a projectile is

A. horizontal B. vertical and downward C. zero D. vertical and upward E. equal to the launch velocity

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