1 Answer is in the image ..
2. electronic configuration of ,
i)oxygen = 2,6
3.law of constant proportion was introduced by PROUST . This law states that in a chemical compound elements combine in a small whole no. in ratio of fixed proportion by mass.
for example : In compound NH3 elements N and H are in the fixed ratio of 14:3
5.He must pass ultrasonic waves from the building walls of they pass undeflected then there is no crack present but if gets deflected then there is a crack present.
8.Velocity=72kmph =72*5/18=20 m/s
kinetic energy= 1/2mv^2
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