Q$(1)$:

When the initial deficit is zero, the deficit at any point is proportional to

a$.$ The initial BOD

b$.$ Downstream BOD

c$.$ Minimum DO

d$.$ Maximum DO

e$.$ All mentioned

Q$(2)$:

$2.$ The Nitrogen oxide formed according to the following equation is known as

air$+$ heat$=$NOx

$($ a$)$ Fuel NOx $($ d$)($b$)$Industrial NOx

$($ c$)$ Combusted NOx

$($ d$)$ Anthropogenic NOx

$($ e$)$ Thermal NOx