The emission spectrums are known for the elements below. Line spectra for boron, lithium, hydrogen, helium, potassium and unknown sample. Boron has 3 purple lines, 1 blue line, 2 blue-green lines and 2 orange lines. Lithium has 2 purple lines, 2 blue lines, 2 blue-green lines, 1 orange line and 1 red line. hydrogen has one line of each purple, blue, blue-green and red. helium has 3 purple lines, 3 blue lines, 3 blue-green lines 1 yellow line and 2 red lines. Potassium has 8 purple lines, 6 blue-green lines, 10 green lines, 3 yellow lines, 2 orange lines and 6 red lines. The unknown sample has Potassium has 8 purple lines, 6 blue-green lines, 10 green lines, 3 yellow lines, 2 orange lines and 6 red lines. What elements are in the unknown sample? Check all that apply. boron lithium hydrogen helium potassium

The Answer is (B) lithium and (E) potassium

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

increased stability in the completion of fluorine's outer shell.