Which one of the following statements is...

Which one of the following statements is not true-----

oxides of sulphur, nitrogen and carbon are the most widespread air pollutant

pH of drinking water should be between 5.5-9.5

concentration of DO below 6 ppm is good for the growth of fish

clean water would have a BOD value of less than 5 ppm

Verified by Experts

Growth offish is facilitated if the DO value is less than 6 ppm. Decrease in Do value means increase in water pollution.

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Which one of the following statements is true ?

A scalar quantity is the one that is conserved in a process

A scalar quantity is the one that can never take negative values

A scalar quantity is the one that does not vary from one point to another in space

A scalar quantity has the same value for observers with different orientations of the axes.

the valence band of Na metal is partially filled

in case of Mg metal, the conduction band overlaps with the valence band

the electrical conductivity of a semiconductor increases with rise in temperature

the electrical conductivity of a metal increases with rise in temperature

paramagnetic substances are weakly attracted by magnetic field

ferromagnetic substances cannot be magnetised permanently

the domains in anti-ferromagnetic substances are oppositely oriented with respect to each other

pairing of electrons cancels their magnetic moment in the diamagnetic substances