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The diameter of a ring is 19mm. Calculate the area of the ring in cm^2, giving the area to 3 significant figures.

First you must convert the diameter into cm from mm:19/10 = 1.9cmThen you must find the radius of the ring:radius = diameter/2 = 1.9/2 = 0.95 cmThen you can calculate the area:area = 2πr 2 = 2 x π x (0.95) 2...
MP
Answered by Mary P. • Maths tutor
4038 Views

Donnez des exemples de ce que vous aimez faire pendant votre temps libre.

Pendant mon temps libre j'aime faire beaucoup de sport parce que c'est mon intention de rester toujours en forme. Depuis ma jeunesse, j'ai eu une passion pour le tennis car je regardais les meilleurs profess...
LG
Answered by Louis G. • French tutor
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Different enzymes catalyse specific reactions. Explain why enzymes can only catalyse specific reactions.

A simple way of thinking about why enzymes catalyse only specific reactions is to think of the enzyme and the substrate (the compound the enzyme is acting upon) as a lock and key system. Enzymes have a parti...
OD
Answered by Oliver D. • Biology tutor
9855 Views

Solve the simultaneous equation: 2x + y = 18, x - y = 6

First, we simply label the two equations as 'Equation 1' and 'Equation 2' respectively. So we have: Equation 1: 2x + y = 18and Equation 2: x - y = 6. In simultaneous equations, there are two variables: x and...
HM
Answered by Harry M. • Maths tutor
4864 Views

25 cm3 of NaOH was titrated with 0.050 mol dm-3 HCl. NaOH + HCl --> NaCl + H2O. 21.5 cm3 HCl neutralised 25 cm3 NaOH. Concentration of NaOH in mol dm-3?

21.5 cm 3 / 1000 = 0.0215 dm 3 of HCl. n = cv so (0.050) x (0.0215) = 0.001075 mols of HCl. NaOH + HCl --> NaCl + H 2 O so there is a 1:1 ratio of reactants to products. Therefore there are 0.001075 mols ...
AS
Answered by Arran S. • Chemistry tutor
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