Which one of the following is used as an acid flux in metallurgy?

If the straight lines $2x + 3y - 1 = 0$,$x + 2y - 1 = 0$ and $ax + by - 1 = 0$ form a triangle with the orthocentre at the origin,then $(a, b) =$

Wires $P$ and $Q$ have the same resistance at ordinary (room) temperature. When heated,the resistance of $P$ increases and that of $Q$ decreases. We conclude that

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

The total number of $RNA$ strands in an animal virus is:

Doping silicon with boron produces a