The pH of lemon juice at 298 K is found to be 2.32. What is the concentration of ions in the solution?
Use StartBracket upper H subscript 3 upper O superscript plus EndBracket equals 10 superscript negative p H..
1.05 times 10 to the negative 3 moles per liter.
4.79 times 10 to the negative 3 moles per liter.
2.09 times 10 squared moles per liter.
9.55 times 10 squared moles per liter.

let that person have a turn to speak : )

the answers would be

the first one and the second one

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answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.