Widal test is used for the diagnosis of

The Earth $E$ moves in an elliptical orbit with the Sun $S$ at one of the foci as shown in the figure. Its speed of motion will be maximum at the point:

What is the formula of Carborundum?

Which of the following statements is not correct?

If the equation $ax^2 + 2hxy + by^2 + 2gx + 2fy + c = 0$ represents a pair of straight lines,then the square of the distance of their point of intersection from the origin is

Which of the following processes does not use a catalyst?