Class 11th

A spherical gas balloon of radius 16 meter subtends an angle 60° at the eye of the observer A while the angle of elevation of its center from the eye of A is 75°. Then the height (in meter) of the top most point of the balloon from the level of the observer's eye is:

Let an ellipse E: x²/a² + y²/b² = 1, a² > b², passes through (√3/2, 1) and has eccentricity 1/√3. If a circle, centered at focus F(α, 0), α > 0, of E and radius 2/√3 intersects E at two points P and Q, then PQ² is equal to:

The Boolean [removed]p ⇒ q) ∧ (q ⇒ ¬p) is equivalent to:

Consider the following reactions, which of these reaction(s) will not produce Saytzeff product?
(a) (CH?)?CCH(OH)CH? --(cons. H?SO?)-->
(b) (CH?)?CHCH(Br)CH? --(cons. KOH)-->
(c) (CH?)?CHCH(Br)CH? --((CH?)?CO?K?)-->
(d) (CH?)?C(Br)-CH?-CHO --(Δ)-->
Which of these reaction(s) will not produce Saytzeff product?

The order of electron gain enthalpy in kJ/mol of fluorine, chlorine, bromine and iodine, respectively are

Given that the standard potential (E°) of Cu²?/Cu and Cu?/Cu are 0.34 V and 0.522 V respectively, the E° of Cu²?/Cu? is

1-methyl ethylene oxide when treated with an excess of , produces

What is the product of following reaction?

Let $X=\{n\in N:1\le n\le 50\}$ . If $A=\{n\in X:n$ is a multiple of 2 $\}$ and $B=\{n\in X,n$ is a multiple of 7 $\}$ , then the number of elements in the smallest subset of $X$ containing both $A$ and $B$  is

If the mean and variance of eight numbers $\mathrm{3,7},\mathrm{9,12,13,20}$ , $x$ and $y$ be 10 and 25 respectively, then $xy$  is equal to