Which one of the following wavelength radiations may correspond to an X-ray ?
- A.1 nm
- B.10 nm
- C.100 nm
- D.300 nm
Correct answer
Explanation
The correct answer is A, 1 nm. X-rays have wavelengths from about 0.01 nm to 10 nm, so 1 nm lies well inside the X-ray band.
In the electromagnetic spectrum, wavelength decreases from radio waves through microwaves, infrared, visible light and ultraviolet to X-rays and gamma rays. Visible light spans about 400 to 700 nm, and ultraviolet lies roughly between 10 nm and 400 nm. Because their wavelength is so short, X-rays carry high energy and pass through soft tissue but are stopped by bone, which is why they are used to take images of bones.
B is wrong: 10 nm marks the boundary between X-rays and ultraviolet and is usually treated as extreme ultraviolet.
C is wrong: 100 nm is ultraviolet radiation.
D is wrong: 300 nm is also ultraviolet, close to the visible range.
Exam tip: gamma rays are shortest, then X-rays (0.01 to 10 nm), ultraviolet (10 to 400 nm), visible light (400 to 700 nm) and infrared.
Practice Questions
View allSyngamy results in formation of
- A.haploid zygote
- B.diploid zygote
- C.non-motile male gametes
- D.motile male gametes
Show answer
Syngamy is the fusion of a male and a female gamete, and since each gamete is haploid, their union gives a diploid zygote.
Read the full explanation →Human insulin molecule is composed of one α-chain having 21 amino acids and one β-chain having 30 amino acids. How many functional insulin genes occur in adult humans?
- A.One
- B.Two
- C.Three
- D.Four
Show answer
Humans have a single functional insulin gene, INS, on the short arm of chromosome 11, and both chains of insulin come from it.
Read the full explanation →Which one of the following is the value of one nanometer?
- A.10⁻⁷ cm
- B.10⁻⁶ cm
- C.10⁻⁴ cm
- D.10⁻³ cm
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One nanometre is 10⁻⁹ metre, and since one metre is 100 (10²) centimetres, it equals 10⁻⁷ centimetre. The prefix nano means one billionth.
Read the full explanation →Which of the following is the general formula for saturated hydrocarbons?
- A.CₙH₂ₙ₊₂
- B.CₙH₂ₙ₋₂
- C.CₙH₂ₙ₊₁
- D.CₙH₂ₙ₋₁
Show answer
Saturated open-chain hydrocarbons are the alkanes, and every alkane fits the formula CₙH₂ₙ₊₂. In a saturated hydrocarbon every carbon atom is joined to others only by single bonds, so each carbon holds the largest possible number of hydrogen atoms.
Read the full explanation →Which one of the following is not an epidemic disease?
- A.Cholera
- B.Malaria
- C.Smallpox
- D.Elephantiasis
Show answer
Elephantiasis, or lymphatic filariasis, is an endemic disease: it stays steadily present in certain regions and develops slowly over years, rather than breaking out suddenly in a large number of people.
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