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Write a word equation for the reaction between marble chips and hydrochloric acid. (1) How could the rate of reaction be increased and why? (7)

i) Marble chips are made from calcium carbonate.Hydrochloric acid + calcium carbonate -> Calcium chloride + water + carbon dioxideii) The rate of reaction can be increased by increasing the concentration ...
MK
36705 Views

Solve 2x^2+ 7x -8 = 0, giving your answer to 2 decimal places.

You can solve this equation using the quadratic formula: x = -b +/- root(b 2 - 4ac) 2aSo, a=2, b=7, c=-8:x = -7 +/- root(7 2 - 4 x 2 x -8) 2 x 2So, x = 0.31 or -3.81
MK
Answered by Michelle K. • Maths tutor
8743 Views

Find the exact solution, in its simplest form, to the equation ln(4y + 7) = 3 + ln(2 – y) (Core Maths 3 Style Question)

First we subtract ln(2-y) from both sides to get "ln(4y+7) - ln(2-y) = 3". By applying the laws of logs from C2, we have "ln[(4y+7)/(2-y)] = 3". Therefore, if we put them as exponents of ...
DB
Answered by Danielle B. • Maths tutor
4651 Views

Prove algebraically that 
(2n + 1)^2 – (2n + 1) is an even number for all positive integer values of n. (3 marks)

We can show something is even if it is a multiple of two, as every multiple of two is even. It is useful to see certain tricks, and I will aim to teach you these in my tutorials, these tricks make problems e...
BH
Answered by Ben H. • Maths tutor
7240 Views

Describe how phagocytosis of a virus leads to presentation of its antigens (3 marks)

Virus engulfed by phagocyte (broad immune response), destroyed using lysosomes (hydrolysis) and viral antigens presented on cell membrane (trigger specific immune response e.g. anti-bodies). Steps of phagocy...
BJ
Answered by Ben J. • Biology tutor
28081 Views