List of top Questions asked in GATE Environmental Science and Engineering

A gravity settling chamber of height ‘H' and length ‘L' is designed to control particulate air pollution. In the chamber, the horizontal velocity of air flow is $'V_h'$ and terminal settling velocity of the target particle is $'V_ť$. Which one of the following expressions is the correct concept used to calculate the minimum size of the target particle that will be removed with 100% efficiency?

With reference to disinfection, which of the following statement(s) is/are CORRECT?

Which one is the solution y(x) for the following ordinary differential equation and the specified boundary conditionmys?
\(\frac{d^2y}{dx^2} -3 \frac{dy}{dx}+2y = 2e ^{-x}; y(0) =2; (\frac{dy}{dx}_{x=0})=1\)

A municipal solid waste digester generates 1000 kg of methane gas. The volume of the tank needed to store this gas at 30°C and 3 atmospheric pressure is ________ liters (an integer value).
Use R=0.082 L-atm/mole-K, Atomic weights of C=12, and H=1

A population (with mean μ) follows normal distribution. Ten samples (N) are drawn at random with a mean value of "x" and standard deviation of "S". Following table provides the confidence limits, C(t) of the cumulative probability function for Student's t - distribution two-tailed test with degree of freedom, D.
Which one of the following expression is correct for testing the null hypothesis $H_o: μ = 0$ at 10% significance level?

D	C(t)
	0.9	0.95	0.975
9	1.38	1.83	2.26
10	1.37	1.81	2.23
11	1.36	1.80	2.20

A Class-A pan was setup adjacent to a lake for measuring evaporation losses in the lake. The depth of water in the pan at the beginning of a certain week was 250 mm. In that week, there was a rainfall event with 10 mm depth. Water depth in the pan at the end of the week was 240 mm. The pan coefficient is 0.8.
The estimated lake evaporation during the week was |_________mm (an integer value).

Consider second order kinetics ($r = −kC^2$) under steady state condition. The ratio of volume of a complete mixed reactor (CMR) to that of a plug flow reactor (PFR) to achieve 90% reduction in the concentration is _______ .
Inlet concentrations in both the reactors are same.

Consider the equation - $\farc{dy}{dx}- x^2 + e^x = 0;$ with y =1 at x = 0.
The value of y at x = 1 is _________. (rounded off to 2 decimal places).
Take the value of e (base of natural logarithm) as 2.7.

As per the Hazardous Waste (Management and Handling) Rules, 2016, of India, which is/are the characteristic(s) that must be exhibited by a waste to be classified as a "characteristic" hazardous waste?

The equipment that can be used to control particulate air pollution in an industrial unit is/are

$f(x) = x^3 – 4.5x^2 - 12x$ has a local maximum at x = ___________(an integer value) in the range x = − 2 to + 2

With respect to particle settling in wastewater treatment systems; the correct statement(s) is/are

Which is/are the secondary air pollutant(s)?

In a rectangular open channel, the flow is critical, and the flow depth is 2 m. Select the correct statement(s)

In the context of fluid flow, which of the following statement(s) is/are correct?

The costliest functional element in an urban centralized Municipal Solid Waste management infrastructure for a typical Indian Tier I city is ________.

The eigen values of the matrix \(\begin{bmatrix}4 & 3 \\3 & 4 \end{bmatrix} \) are

As per the United Nations Environmental Program (UNEP) guidelines 2004, the maximum size of microplastics is ________.

Which one of the following is NOT a greenhouse gas?

If X is a vector, and A and B are linear operators; then the correct mathematical relationship(s) is/are

The environmental temperature increases by 6°C/km with height at a particular location. The stability condition of the atmosphere at the location is ______,

Crown corrosion of reinforced cement concrete sewer is caused by ______

As per the United Nations agenda for sustainable development adopted in September 2015, the number of Sustainable Development Goals (SDGs) _____ are year to achieve them is and the proposed target year to achieve them is ______.

The processes of removal of particles in a rapid sand filter with their description is given in the table.

Process	Description
(i) Straining	P: Removes only particles in the water large enough to get caught in the pores of the filter
(ii) Sedimentation	Q: Larger and heavier particles do not follow the fluid streamline around the sand grain and settle on the grain
(iii) Interception	R: Particles that do follow the streamline, but are too large and are caught because they brush up against the sand grains
(iv) Diffusion	S: Very small particles are experiencing Brownian motion and may collide with the sand grains by chance

Select the correct match.

Tuberculosis is predominantly caused by ________.