If the lines $x^2+2xy-35y^2-4x+44y-12=0$ and $5x+\lambda y-8=0$ are concurrent,then $\lambda$ equals

Which option is correct to match section $A$ with section $B$?

Section $A$	Section $B$
$(i)$ Nitrosomonas	$(a)$ $\text{Nitrite} \rightarrow \text{Nitrate}$
$(ii)$ Agrobacterium	$(b)$ $\text{Nitrogen fixing bacteria}$
$(iii)$ Rhizobium	$(c)$ $\text{NO}_3^- \rightarrow \text{N}_2$
$(iv)$ Nitrobacter	$(d)$ $\text{Ammonia} \rightarrow \text{Nitrite}$
	$(e)$ $\text{Denitrifying bacteria}$

$ ( X ) + K_2CO_3 + Air \xrightarrow{heat} ( Y ) $
$ ( Y ) + Cl_2 \longrightarrow ( Z ) $ Pink
Which of the following is correct ?

Which one of the following statements is correct?

In a $\triangle ABC$,the expression $\frac{(a+b+c)(b+c-a)(c+a-b)(a+b-c)}{4b^2c^2}$ is equal to:

An observer moves towards a stationary source of sound with a speed $1/5^{th}$ of the speed of sound. The wavelength and frequency of the source emitted are $\lambda$ and $f$ respectively. The apparent frequency and wavelength recorded by the observer are respectively: