Ravi suggested his friend Karim the following ways to reduce or minimise friction. (i) Smoothening the surfaces in contact. (ii) applying lubricants between the surfaces (iii) streamlining the bodies of objects moving in fluids (iv) Applying coarse material between the surfaces is contact. Which of the methods suggest is correct? Options :
(i) and (iv)
only (iv)
(ii) and (iii)
(i), (ii) and (iii)

3rd option

Explanation:

According to modern theory of friction, friction cannot be reduced by making smooth. example two mirrors are smooth but if kept in contact there is very high friction. It is due to intermolecular force of attraction but not roughness.

But if you go towards old theory then last option is correct as friction is due to roughness

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hello, i am papaguy.

i have found an answer to your question but use it as information.

information: because weak acids/bases have low concentration of hydrogen ions, the addition of water has a large impact on the ph. 2. a difference in 1 unit is a 10x difference in concentration for example; a liquid with ph of 3 is 10x more acidic than a liquid with a ph of 4. therefore, a liquid with a ph of 3 is stronger.

best of luck!