Which prefix is often used with scientific terms to indicate that something is the same, equal or constant?
Answer: A
The prefix iso- indicates sameness, equality or constancy, from the Greek isos, equal.
Hence isotherm (equal temperature), isobar (equal pressure), isotope (same place in the periodic table) and isomer (same formula). Mega- means large, meta- beyond or changed, and quasi- resembling.
Please log in or register to report this question.
The element required for Solar energy conversion?
Answer: A
Silicon is the element used to convert solar energy to electricity. A photovoltaic cell is a silicon wafer doped to make a p-n junction; light striking it frees electrons that flow as current.
Silicon is used because its band gap of 1.1 eV suits the solar spectrum well and because it is abundant and easily purified.
Please log in or register to report this question.
Which of the following elements is a metal
Answer: D
Gallium (Ga) is the metal. It is a soft, silvery element of group 13 that melts at 29.8°C - low enough to liquefy in the hand.
Sulphur and iodine are non-metals; selenium is a non-metal usually classed with the metalloids.
Please log in or register to report this question.
Who performed the world’s first heart transplant?
Answer: B
Christiaan Barnard performed the world's first human heart transplant, at Groote Schuur Hospital in Cape Town on 3 December 1967.
The patient, Louis Washkansky, lived eighteen days before dying of pneumonia. William Harvey had described the circulation of the blood three centuries earlier.
Please log in or register to report this question.
The Ozone Layer restricts from
Answer: C
The ozone layer blocks ultraviolet radiation.
It absorbs essentially all UV-C and about 90 per cent of UV-B, which would otherwise cause skin cancer and cataracts and damage crops and plankton. Infrared and radio waves pass through it freely.
Please log in or register to report this question.
Bacteria which are round in shape are called-
Answer: C
Round bacteria are cocci (singular coccus), from the Greek for berry.
They occur in pairs as diplococci, chains as streptococci and clusters as staphylococci. Rod-shaped bacteria are bacilli, comma-shaped are vibrios and spiral are spirilla.
Please log in or register to report this question.
Which of the following is not an isotope of hydrogen?
Answer: D
Yttrium is not an isotope of hydrogen - it is a separate element, atomic number 39.
Hydrogen has three isotopes: protium, with one proton and no neutron; deuterium, with one neutron; and tritium, with two, which is radioactive.
Please log in or register to report this question.
The discovery of viruses was made by-
Answer: A
Dmitri Ivanovsky discovered viruses in 1892, showing that the agent of tobacco mosaic disease passed through a filter fine enough to hold back all bacteria.
Beijerinck repeated the work in 1898 and named it a contagious living fluid; Stanley crystallised the virus in 1935.
Please log in or register to report this question.
The age of most ancient geological formation is estimated by?
Answer: D
The most ancient geological formations are dated by the uranium–lead method, which is good to about 4,500 million years.
Uranium-238 decays to lead-206 with a half-life of 4,470 million years, so the ratio of the two dates the rock. Carbon-14, with a half-life of 5,730 years, is useless beyond about 50,000 years and works only on once-living material.
Please log in or register to report this question.
German Silver is an alloy of?
Answer: D
German silver is an alloy of copper, zinc and nickel - typically 60:20:20 - and contains no silver at all.
It is named for its silvery appearance, and is used for tableware, keys of musical instruments and resistance wire.
Please log in or register to report this question.
