4306. An element of atomic no. 29 belongs to
| Answer : Option C |
| Explanation : |
| d-block.Copper (Cu) has the atomic number of 29. Most of the d-block elements are considered to be metals, with a common lustrous metallic appearance. Copper belongs to the d-block which is the collective name for Groups 3 to 12 in the periodic table. |
4308. The pitch of sound depends on its
| Answer : Option D |
| Explanation : |
| Frequency. Pitch is a perceptual property that allows the ordering of sounds on a frequency-associated scale. When the frequency is high, the wavelength of the sound is shorter. Pitch may be quantified as a frequency, but pitch is not a purely goal physical property; it is a subjective psychoacoustical attribute of sound. |
4309. The element first detected spectroscopically in the Sun's atmosphere is
| Answer : Option A |
| Explanation : |
4310. KMnO4 can be used as a/an
| Answer : Option B |
| Explanation : |
| Potassium permanganate is an inorganic chemical compound with the formula KMnO4. As an oxidant, potassium permanganate can act as an antiseptic. For example, dilute solutions are used to treat canker sores (ulcers), disinfectant for the hands & treatment for mild pompholyx,dermatitis, & fungal infections of the hands or feet. It is used vastly in the water treatment industry. |
4311. If density of oxygen is 16 times that of hydrogen, what will be their corresponding ratio of velocity of sound -
| Answer : Option A |
| Explanation : |
| The velocity of sound in a gas is given by v = g r p.... (i) Clearly, velocity v is inversely proportional to the square root of density (r) of the gas.Now, let us consider two gases which are at the same pressure (P) & the same value of g. If r1 & r2 be their densities, then velocity of sound in the two gases are v1 = g r p 1 & v2 = g r p 2 \ v v 1 2 2 1 = r r.... (ii) For example, density of oxygen is 16 times the density of hydrogen, so from (ii), we have v v pH PpH H o H = = = r r 0 16 4 or v v H = 4 0 So the corresponding ration of velocity of sound in oxygen & hydrogen is 1:4. |
4312. The anode of a dry cell is made up of
| Answer : Option A |
| Explanation : |
| Zinc.A standard dry cell comprises a zinc anode (negative pole), usually in the form of a cylindrical pot, with a carbon cathode (positive pole) in the form of a central rod. The remaining space between the electrolyte & carbon cathode is taken up by a 2nd paste consisting of ammonium chloride & manganese dioxide, the latter acting as a depolariser. The electrolyte is ammonium chloride in the form of a paste next to the zinc anode. |
4313. The chief source for the production of nitrogeneous fertilizers is:
| Answer : Option D |
| Explanation : |
| Ammonia.Nitrogen fertilizers are often made using the HaberBosch process which uses natural gas (CH4 +) for the hydrogen & nitrogen gas from the air at an elevated temperature & pressure in the presence of a catalyst toform ammonia as the end product. This ammonia is used as a feedstock for other nitrogen fertilizers, such as anhydrous ammonium nitrate & urea. |
4314. The frequency of ultrasound wave is typically
| Answer : Option D |
| Explanation : |
| Below 20 kHz.Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Although this limit varies from person to person, it is approx. Ultrasound is so not separated from 'normal' (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. |
4315. An object which absorbs all colours & reflects none appears:
| Answer : Option D |
| Explanation : |
| A surface that absorbs all colours, reflecting none, is said to be black. Black is not a colour; it absorbs all the colours of the visible spectrum & reflects none of them to the eyes. White is a colour. |
4316. The chemical name of 'Plaster of Paris' commonly used for setting broken bones is
| Answer : Option B |
| Explanation : |
| Calcium sulphate.Plaster of Paris is the common name of Calcium Sulphate hemihydrate, with chemical formula: CaSO4. Plaster of Paris is produced by heating gypsum to about 150°C.1/2H2O. |
4317. 'Fire-fighting clothes' are made from
| Answer : Option D |
| Explanation : |
| Asbestos.Bunker Gear or Turnout Gearare terms used by many firefighters to refer to their system of outer protective clothing. As of its carcinogenic properties & other harmful effects" |
4318. The 'Green House effect' is produced due to the presence of excess amount of
| Answer : Option D |
| Explanation : |
| By their percentage contribution to the greenhouse effect on Earth the four major gases are: Water vapour (36-70%), Carbon dioxide (9-26%), Methane (4-9%) |
4319. A car starts from rest and moves on a straight road with a uniform acceleration of 10 m/s2 for the first 10 s. During the next 10 s, the car moves with the velocity it has attained. What is the total distance covered by the carin 20 s?
| Answer : Option A |
| Explanation : |
4320. Which among the given waves cannot be polarised -
| Answer : Option D |
| Explanation : |
| Only transverse waves (such as radio, ultraviolet & infrared waves) can be polarized since their vibrations can potentially occur in all directions perpendicular to the direction of travel. It is so possible to confine the vibrations to a single plane. However, sound waves are longitudinal in which vibrations are parallel to the direction of travel of the wave. The vibrations of a longitudinal wave occur along a single line, it is so not possible to confine that to a plane. So it cannot be polarized. |
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