Daily NEET MCQ- May 1, 2022 - NEET MCQ

As the air is moving, we can solve this question from the air’s frame of reference. From the air’s frame of reference, the observer will be going towards the observer at 2m/s and the source will be coming towards the observer at 10-2 = 8m/s.
F = f(v+v₀)/(v+v₈)
= 20(330+2)/(330-8)
= 20*332/322 = 20.62Hz.

Speed of sound in the medium depends on the properties of the medium like bulk modulus and density, not on the speed of source creating the sound.

Apparent frequency F = f(330+v₀)/(330+v₈)
= 10(330)/(330-10) = 10.31Hz.
Wavelength = 330/F
= 330/10.31
= 32.007m = 32m.

Apparent frequency only depends on velocity and not the distance between source and observer. So, maximum frequency will be heard when speed is maximum, which is at the start. F = 50(330)/(330-20)
= 53.22Hz.

We can find the speed corresponding to the apparent frequency and then use that to find the height of the building.
120 = 100(330)/(330-v) v = 330 – 3300/12 = 55m/s.
Using, v² = 2gh, we can find the height covered by the man. The double of this value will be the height of the building as he is mid-way.
55² = 2*9.81*h h = 154m Height of building = 2h = 308m.

Ethanal can be prepared by oxidation of ethene, in the presence of an ionic catalyst in an aqueous medium. This is a greener method and gives 90% of yield.

Synthetic methods should avoid using or generating substances toxic to humans and/or the environment. Hence less hazardous chemical synthesis is an important principle.

Chlorine gas was used to bleach paper. It has good oxidizing properties. Nowadays H₂O₂ with a suitable catalyst is used for bleaching purposes as it does not contaminate groundwater.

The atria are the two upper chambers of the heart. The walls of the atria secrete a hormone known as atrial natriuretic factor or ANF. Its function is to reduce blood pressure to maintain homeostasis.

Atrial natriuretic factor or ANF is secreted by the walls of the atria of the heart. Its effect is to dilate blood vessels and hence decrease blood pressure. Adrenaline and noradrenaline increase blood pressure.