If $\frac{x^2+x+1}{x^2+2x+1} = A + \frac{B}{x+1} + \frac{C}{(x+1)^2}$,then $A-B$ is equal to

In the context of the lanthanoids,which of the following statements is not correct?

Which of the following is the most stable ecosystem?

Calculate $\Delta H$ in $kJ$ for the following reaction:
$C_{(g)} + O_{2(g)} \longrightarrow CO_{2(g)}$
Given that:
$H_2O_{(g)} + C_{(g)} \longrightarrow CO_{(g)} + H_{2(g)} ; \Delta H = +131 \ kJ$
$CO_{(g)} + \frac{1}{2} O_{2(g)} \longrightarrow CO_{2(g)} ; \Delta H = -282 \ kJ$
$H_{2(g)} + \frac{1}{2} O_{2(g)} \longrightarrow H_2O_{(g)} ; \Delta H = -242 \ kJ$

The equation of the parabola with focus $(0,0)$ and directrix $x+y=4$ is

The following observations were taken for determining the surface tension $T$ of water by the capillary method:
Diameter of capillary,$D = 1.25 \times 10^{-2} \ m$
Rise of water,$h = 1.45 \times 10^{-2} \ m$
Using $g = 9.80 \ m/s^2$ and the simplified relation $T = \frac{rhg}{2} \times 10^3 \ N/m$,the possible error in surface tension is closest to ......... $\%$