Class 11th

The Lanthanoid that does not show +2 oxidation states is:

Two carnot engines operate in series between a heat source at a temperature $T_1=900\mathrm{K}$ and heat sink at temperature $T_3=400\mathrm{K}$ . There is another reservoir at temperature $T_2$ , as shown, with $T_1>T_2>T_3$ . The two engines are equally efficient if $T_2=$ K 

What is the molecular weight of the final product in the following reaction sequence

Total number of species in which atleast one atom have same hybridization as in central atom of azide ion.

N₂O, C₂H₂, CO₂, C₃O₂, BeF₂, NO₂, PF₃

A hot body is being cooled in air according to Newton's law of cooling, the rate of fall of temperature being K times the difference of its temperature with respect to that of surroundings. The time after which the rate of heat loss of the body will be half of the maximum rate of heat loss is $\frac{1}{2k}{\mathrm{l}\mathrm{o}\mathrm{g}}_e?n$ (The time is to be counted from the instant t = 0 ). The value of n is

The set that contains atomic numbers of only inner transition elements is:

A 1kg particle is moving unidirectionally on a horizontal plane under the action of power $P=-2v^3$ , of power supplying energy source. The velocity (v) - time (t) graph that describes the motion of the particle is shown in figure. (Graphs are drawn schematically and are not to scale) The value of $t_0$  in graph is sec. Find 8x

An organic compound P contains 62.07% carbon and 10.34% hydrogen and rest oxygen. Its vapour density is 29. This compound does not react with sodium meta, but its 2.9g combine with Xg of bromine (to give dibromo addition product). Find out value of (Y-X). (Where Y is total number of possible isomers of given organic compound P)

[Atomic mass : Br = 80]

Among the following the total number of elements which produce H₂ gas with NaOH is Zn, Al, Sn, Pb, P, S