Question 4 (higher question) Electrolysis of acidified water can produce hydrogen and oxygen.
The apparatus for the electrolysis is:
. water containing some dilute sulfuric acid
• two graphite rods
• a suitable container for the electrolysis reaction
. a suitable source of electricity
• test tubes
Describe how to use the apparatus to electrolyse acidified water, and how to test the gases to
show that they are hydrogen and oxygen. Include a diagram in your answer. [6 marks]

Explanation:

Describe means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.

Explain means you need to make something clear, or state the reasons for something happening.  

Compare means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y, and give a comparison. Do not just write about X only or Y only.

Evaluate means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.

what is the general relationship between a galaxy's distance from earth and its speed?

the answer is:

the farther away a galaxy is from us, the faster it is moving away from us.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.