A train is sounding its horn as it approaches a station. The engine driver hears a note of frequency f0 and of constant amplitude as the train slows down and…

Calcium nitride, Ca 3N2 , reacts with water to form calcium hydroxide and molecule X. No other products are formed, and molecule X contains only nitrogen and hydrogen atoms. What…

The family tree shows the inheritance of a recessive condition. Which of the following statements is/are correct?1 Individuals 1 and 2 are both heterozygous for this condition.2 Individuals 3 and…

A circle is drawn with centre (3, 5). A tangent is drawn to the circle. The tangent touches the circle at the point (6, 7). What is the gradient of…

A high-voltage dc overhead cable carries a current of 2000 A. One 20 m section of the cable has a mass of 120 kg. This cable section is supported so…

Three elements from Group 1 and three elements from Group 17 are given in the table with their relative atomic masses.Group 1 Group 17lithium (7) fluorine (19)sodium (23) chlorine (35.5)potassium…

A nucleotide consists of three different sub-units. A section of double-stranded DNA consists of 600 of these sub-units in total. Of these sub-units, 28 are the base adenine. What percentage…