Answer:
Mendeleev predicted the atomic mass of each element along with compounds they each should form.
Explanation:
Based on other elements in the same group he predicted the existence of eka-aluminum and eka-silicon, later to be named gallium (Ga) and germanium (Ge).
Answer:A
Explanation:Find attached picture file for details
Answer:
the difference between the two is that the candle forms an emission spectrum and the book an absorption spectrum.
the book it is observed in all directions so that its reflection has to be diffused
Explanation:
The ray of light emitted by a candle is the light generated by the temperature of the flame, which is made up of the emissions of a black body at this temperature plus the emissions of the chemical elements that make up the candle.
The Light reflected from the cover of a book is the same incident light spectrum minus the wavelengths that create transitions in the elements of the cover, these wavelengths will be seen as dark areas.
As a consequence of the above, the difference between the two is that the candle forms an emission spectrum and the book an absorption spectrum.
For the cover of the book form a specular reflection the incident rays are reflected in one direction and the rest would be dark, but in the book it is observed in all directions so that its reflection has to be diffused
As we know that

here we know that


now from above equation we have


so image will form on left side of lens at a distance of 15 cm
This image will be magnified and virtual image
Ray diagram is attached below here
Answer:
f3 = 102 Hz
Explanation:
To find the frequency of the sound produced by the pipe you use the following formula:

n: number of the harmonic = 3
vs: speed of sound = 340 m/s
L: length of the pipe = 2.5 m
You replace the values of n, L and vs in order to calculate the frequency:

hence, the frequency of the third overtone is 102 Hz