Which one of the following types of radiation has the shortest wavelength?
- A.Radio waves
- B.Visible light
- C.Infrared (IR)
- D.Ultraviolet (UV)
Correct answer
Explanation
The correct answer is D, Ultraviolet (UV). Of the four, ultraviolet lies furthest towards the short-wavelength, high-energy end of the electromagnetic spectrum.
All electromagnetic waves travel at the speed of light in vacuum, but they differ in wavelength and frequency. In order of decreasing wavelength the spectrum runs: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays. Visible light spans roughly 400 to 700 nanometres, from violet to red. Ultraviolet begins just beyond violet, below about 400 nm, which is why it has more energy per photon and can cause sunburn. Infrared starts just beyond red, above about 700 nm, and radio waves can be metres or even kilometres long.
A is wrong: radio waves have the longest wavelengths in the spectrum.
B is wrong: visible light is longer in wavelength than ultraviolet.
C is wrong: infrared is longer in wavelength than both visible light and ultraviolet.
Exam tip: long to short wavelength: radio, micro, IR, visible, UV, X, gamma; energy and frequency rise in the same order.
Practice Questions
View allWhich one of the following is the 'energy currency' for cellular processes?
- A.Glucose
- B.ATP
- C.ADP
- D.Pyruvic acid
Show answer
Adenosine triphosphate stores energy in its phosphate bonds and releases it wherever the cell needs it, so it is called the energy currency of the cell.
Read the full explanation →Which one of the following is the correct reactivity order of metals reacting with dilute HCl?
- A.Mg > Al > Zn > Fe
- B.Mg < Al < Zn < Fe
- C.Mg > Zn > Fe > Al
- D.Fe > Mg > Al > Zn
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This is the order in which these metals stand in the reactivity series, and it matches how vigorously they release hydrogen from dilute hydrochloric acid.
Read the full explanation →Deficiency of iron causes
- A.Anaemia
- B.Scurvy
- C.Rickets
- D.Cholera
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Iron is needed to make haemoglobin, so too little iron means too little haemoglobin and a reduced ability of the blood to carry oxygen.
Read the full explanation →Consider the following statements regarding waves : 1. If the particles of a medium move along the direction of motion of the wave, the wave is called a longitudinal wave. 2. If the particles of a medium move perpendicular to the direction of motion of the wave, the wave is called a transverse wave. 3. Transverse waves may involve change in the shape of the medium, whereas longitudinal waves involve change in the density of the medium. Which of the statements given above is/are correct ?
- A.1 and 2 only
- B.1 only
- C.2 and 3 only
- D.1, 2 and 3
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All three statements correctly describe how particles move in the two kinds of mechanical waves. In a longitudinal wave, such as sound in air, the particles vibrate back and forth along the direction in which the wave travels.
Read the full explanation →In paper manufacturing, degumming of the raw material is done using
- A.sulphuric acid
- B.bleaching powder
- C.caustic soda
- D.nitric acid
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In paper making the raw plant material is cooked with caustic soda, which dissolves the gums, resins and lignin that bind the cellulose fibres together.
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