The diagram shows some stages involved in genetic engineering. Which row correctly identifies W, X, Y and Z? Answer: 1) E W is a section of the chromosome. It is…

The radioactive isotope carbon-14 is found in living material in small quantities. There areapproximately 1000 carbon-14 atoms for every 10 15 carbon-12 atoms. Whilst the material is stillliving this ratio…

Xenon gas reacts with fluorine gas to form gaseous xenon hexafluoride at high temperatureand pressure. The overall energy change is − 330 kJ / mol.Under these conditions, the F –…

In a type of fruit fly the brown body colour allele is dominant to the black body colour allele. A male fruit fly heterozygous for body colour and a female…

Which one of the following is a simplification of x/x-1 - x2+3/ x2 +2x-3? Answer:

The radioactive isotope plutonium-244 becomes radon-220 after a succession of decays. The atomic number of plutonium is 94 and the atomic number of radon is 86. How many alpha particles…

A compound of oxygen and fluorine has a relative molecular mass which is twice that of its empirical formula mass. 105 g of the compound contains 57 g of fluorine.…

An animal cell is surrounded by a very dilute glucose solution which has a lower concentration of glucose than the glucose solution in the cytoplasm of the cell. There is…

The mean mass of a sweet in a bag of 20 sweets must be greater than 10 grams but not greater than 10.5 grams. A bag is being filled with…

A circuit consists of a 10 Ω resistor and a variable resistor connected in series with a 6.0 V battery. The variable resistor has a minimum resistance of 2.0 Ω…