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Look at this diagram of a methane molecule. Which statement about methane is correct? - A) Electrons are transferred from hydrogen atoms to carbon atoms. - B) The covalent bonds in methane are weak.

(didn't fit:)C) The force of attraction between methane molecules is weak. D) The ionic bonds between carbon and hydrogen are very strong.Answer: C

Answered by Shivani K. • Chemistry tutor

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a) Compare the differences between an artery and a vein. b) List and explain 2 features that allow capillaries to exchange substances efficiently.

a) Veins have a larger lumen and a thinner wall as they carry blood at a lower pressure than the blood in arteries. Due to this low pressure, veins have valves to assist with the continuous movement of bl...

Answered by Zahrah G. • Human Biology tutor

3606 Views

a) What is the function of the atrioventricular valves? b) When the ventricles are contracting, are the arterioventricular valves open or closed? c) Explain why the muscle walls of the atria are thinner than the walls of the ventricles.

a) To prevent backflow of blood from the ventricles into the atria.b) Closedc) The atria only have to pump blood into the ventricles, where as the ventricles have to pump blood at a high pressure all the ...

Answered by Catherine O. • Biology tutor

3101 Views

In a study, researchers had to use different participants in each condition and this could have affected the results. Outline one way in which the researchers could have addressed this issue. 4 marks.

The researchers could have used a matched pairs design in order to create 'experimental twins'. The researchers would first have to identify a variable which may affect the dependent variable - the one be...

Answered by Nicholas G. • Psychology tutor

6592 Views

Please describe how temperature, concentration and the use of a catalyst affects rate of reaction.

For a reaction to be successful two atoms need to collide with a sufficient amount of energy (activation energy). Raising the temperature increases the amount of kinetic energy that the atoms have, which ...

Answered by Georgie S. • Chemistry tutor

2507 Views