the pressure in the tyre is to be increased using a pump.on each stroke of the pump,0.012 mol of air is forced into the tyre. Calculate the number of stroeks of the pump required to increase the pressure to 3.4x10^5 Pa at a temperature of 27 degree Celsius?

You'll need to use the perfect gas law: , you know R, T and P, so you can rearrange it to get n expressed in terms of V, P, R and T

However I'm not sure how you are meant to account for a value of , are there any hints in the question that you are leaving out? It sounds like the volume might have been stated earlier on in the questions...

Let me know if you need further help

You also need the starting pressure. In fact, a dangerous but reasonable assumption would be to consider the volume of the tire to be constant (jack it up). Then the volume and temperature are constants and the variables are P and n. Then assume P1 is one atmosphere. Try it - you are not responsible for the lack of data.