Who proposed the cell theory for plants?

Which of the following is the strongest conjugate base?

$A$ cubical block of wood with a side length of $10 \, cm$ floats at the interface between oil and water,with its lower surface horizontal and $4 \, cm$ below the interface. The density of oil is $0.6 \, g \cdot cm^{-3}$ and the density of water is $1 \, g \cdot cm^{-3}$. The mass of the block is ...... $gm$.

Which of the following cylindrical rods will conduct the most heat when their ends are maintained at the same steady temperatures?

If the area of an equilateral triangle inscribed in the circle $x^2 + y^2 + 10x + 12y + c = 0$ is $27\sqrt{3}$ sq. units,then $c$ is equal to:

The distance between the parallel lines given by $(x+7y)^2 + 4\sqrt{2}(x+7y) - 42 = 0$ is