Option (c) is correct. A mixture of concentrated HNO3 and concentrated HCl is called aqua regia which is also known as "royal water". Aqua regia contains 1 part of concentrated HNO3 by volume with 3 part of concentrated HCl by volume.
Question 13
The equation having -3 as the solution is
(a) x + 3 = 1
(b) 8 + 2x = 3
(c) 10 + 3x = 1
(d) 2x + 1 = 3