Symbol of element was introduced by
- A.John Dalton
- B.Antoine Lavoisier
- C.Jöns Jacob Berzelius
- D.Robert Boyle
Correct answer
Explanation
The correct answer is C, Jöns Jacob Berzelius. The Swedish chemist Berzelius proposed around 1813–1814 that each element be written with one or two letters taken from its name, the system still used today.
Under his scheme the first letter of the element's name, often its Latin name, is written as a capital, and a second small letter is added when two elements share the same initial. That is why sodium is Na from natrium, potassium is K from kalium, iron is Fe from ferrum and copper is Cu from cuprum. Berzelius also worked out accurate atomic weights and discovered elements such as selenium, cerium and thorium.
A, John Dalton, gave the atomic theory and used circular pictorial symbols that were hard to draw, so they were dropped. B, Antoine Lavoisier, named oxygen and hydrogen and stated the law of conservation of mass. D, Robert Boyle, gave Boyle's law and defined an element in The Sceptical Chymist.
Exam tip: Dalton used picture symbols; Berzelius gave the letter symbols such as Na, K and Fe.
Practice Questions
View allA negative work is done when an applied force F and the corresponding displacement S are
- A.perpendicular to each other.
- B.parallel to each other.
- C.anti-parallel to each other.
- D.equal in magnitude.
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Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.
Read the full explanation →Which one of the following statements about a satellite orbiting around the Earth is correct ?
- A.Satellite is kept in orbit by remote control from ground station.
- B.Satellite is kept in orbit by retro-rocket and solar energy keeps it moving around the Earth.
- C.Satellite requires energy from solar panels and solid fuels for orbiting.
- D.Satellite does not require any energy for orbiting.
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Read the full explanation →Which one of the following is not a conservative force ?
- A.Frictional force
- B.Electric force
- C.Gravitational force
- D.Spring force
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Friction is a non-conservative force because the work it does depends on the path taken and the energy it removes is lost as heat.
Read the full explanation →A microphone converts
- A.electrical signals to sound waves
- B.sound waves to electrical signals
- C.microwaves to sound waves
- D.sound waves to microwaves
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A microphone is a transducer that changes the pressure variations of sound into a matching electrical signal. In a common dynamic microphone, sound waves make a thin diaphragm vibrate.
Read the full explanation →When a light ray passes through from air to water with a non-zero angle the ray will be
- A.bending towards the normal
- B.bending away from the normal
- C.propagating in straight line
- D.reflected towards the opposite direction
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Light slows down when it enters water from air, so a ray that strikes the surface at an angle bends towards the normal.
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