Adani's 26/11 connection

When two cells of e.m.f. 1.5 V and 1.1 V connected in series are balanced on a potentiometer, the balancing length is 260 cm. The balancing length, when they are connected in opposition is (in cm)

Two bodies of masses 11kg and 11.5kg are connected by a long light string passing over a smooth pulley Calculate velocity and height ascended/descended by each body at the end of 4s .

The line segment joining the points A,B makes projection 1,4,3 on x,y,z axes respectively then the direction cosiners of AB are (A) 1,4,3 (B) 1/sqrt(26),4/sqrt(26),3/sqrt(26) (C) (-1)/sqrt(26, 4/sqrt(26),3/sqrt(26) (D) 1/sqrt(26),(-4)/sqrt(26),3/(sqrt(26)

When a battery connected across a resistor of 16Omega the voltage across the resistor is 12 V. When the same battery is connected across a resistor of 10Omega voltage. Across it is 11 V. The internal resistance of the battery in ohms is