Which of the following is a polyamide?

If the pair of lines $ax^2 + 2(a + b)xy + by^2 = 0$ represent the diameters of a circle and divide the circle into four sectors such that the area of one sector is three times the area of the other,then:

An ideal gas undergoes a thermodynamic cycle as shown in the figure. Which of the following graphs represents the same cycle?

The population of an insect species shows an explosive increase in numbers during the rainy season,followed by its disappearance at the end of the season. What does this show?

Vapour pressure in $mm \ Hg$ of $0.1 \ mole$ of urea in $180 \ g$ of water at $25^{\circ} C$ is (The vapour pressure of water at $25^{\circ} C$ is $24 \ mm \ Hg$)

The vector $c \cdot (b+c) \times (a+b+c)$ is equal to