If $\theta$ lies in the first quadrant and $5 \tan \theta = 4$,then $\frac{5 \sin \theta - 3 \cos \theta}{\sin \theta + 2 \cos \theta}$ is equal to

Which of the following is known as the $ \text{Christmas Tree} $?

Trees and shrubs have . . . . . . in their bark for gaseous exchange.

The length of the common chord of the circles of radii $15$ and $20$,whose centers are $25$ units of distance apart,is

$A$ cylinder of height $h$ is filled with water and is kept on a block of height $h / 2$. The level of water in the cylinder is kept constant. Four holes numbered $1, 2, 3$ and $4$ are at the side of the cylinder and at heights $0, h / 4, h / 2$ and $3h / 4$ respectively from the base of the cylinder. When all four holes are opened together,the hole from which water will reach the farthest distance on the plane $PQ$ is the hole number

Which reagent is commonly used in titration to determine the hardness of water?