The correct answer is (D):
aR1b ⇔ ab ≥ 0
So, definitely (a, a) ∈ R1 as a2 ≥ 0
If (a, b) ∈ R1 ⇒ (b, a) ∈ R1
But if (a, b) ∈ R1, (b, c) ∈ R1
⇒ Then (a, c) may or may not belong to R1
{Consider a = –5, b = 0, c = 5 so (a, b) and (b, c) ∈ R1 but ac < 0}
So, R1 is not equivalence relation
a R2 b ⇔ a ≥ b
(a, a) ∈ R2 ⇒ so reflexive relation
If (a, b) ∈ R2 then (b, a) may or may not belong to R2
⇒ So not symmetric
Hence it is not equivalence relation
Given below are two statements I and II.
Statement I: Dumas method is used for estimation of "Nitrogen" in an organic compound.
Statement II: Dumas method involves the formation of ammonium sulfate by heating the organic compound with concentrated H\(_2\)SO\(_4\). In the light of the above statements, choose the correct answer from the options given below:
Considering Bohr’s atomic model for hydrogen atom :
(A) the energy of H atom in ground state is same as energy of He+ ion in its first excited state.
(B) the energy of H atom in ground state is same as that for Li++ ion in its second excited state.
(C) the energy of H atom in its ground state is same as that of He+ ion for its ground state.
(D) the energy of He+ ion in its first excited state is same as that for Li++ ion in its ground state.


Ordinary Differential Equations is an equation that indicates the relation of having one independent variable x, and one dependent variable y, along with some of its other derivatives.
\(F(\frac{dy}{dt},y,t) = 0\)
A partial differential equation is a type, in which the equation carries many unknown variables with their partial derivatives.

It is the linear polynomial equation in which derivatives of different variables exist. Linear Partial Differential Equation derivatives are partial and function is dependent on the variable.

When the degree of f(x,y) and g(x,y) is the same, it is known to be a homogeneous differential equation.
\(\frac{dy}{dx} = \frac{a_1x + b_1y + c_1}{a_2x + b_2y + c_2}\)
Read More: Differential Equations