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…
The area of triangle PQR is 42 cm 2 .The length of PR is 8 cm.cos ș = 3/4What is the length of QR, in cm? Answer:
An electric shower heater is rated at 8.4 kW and raises the temperature of flowing water from 16 °C to 36 °C. What is the mass of water passing through…
Dry air can be cooled and then fractionally distilled to separate its components. What is the minimum volume of dry air needed to prepare a 25 dm3 sample of oxygen…
A scientist studying the blue-ringed octopus made the following observations. It inhabits shallow coral reefs where water temperatures are between 26 °C and 29 °C. It feeds on crabs, shrimp…
The line with equation y = – 2 x + 1 is reflected in the line with equation x = 2 Which of the following is the equation of the…
An escalator between two floors in a shop consists of steps that are each 30 cm high and 40 cm deep.There are 20 steps between the floors.The escalator moves a…
Carboxylic acids react with alcohols to make esters. A small amount of concentrated sulfuric acid is used as a catalyst. Consider the following ester: What is the name of the…
The diagram shows changes in the structure of the uterus lining during the menstrual cycle in a healthy female. Two regions are labelled Q and R. S shows when ovulation…