Which of the following is not a correct chemical equation for a double displacement reaction?

a. 2rbno3 + bef2 yields be(no3)2 + 2rbf
b. cacl + lico3 yields caco3 + licl
c. na3po4 + 3koh yields 3naoh + k3po4
d. 2mgi2 + mn(so3)2 yields 2mgso3 + mni4

B. CaCl + LiCO3 yields CaCO3 + LiCl is not correct

It should be CaCl2 + Li2CO3  → 2LiCl + CaCO3

Explanation:

For a reaction to be double displacement reaction there are two things we need to look for

1) There must be an interchange of the group of ions

2) The reactants must dissolve in water to release ions

A. 2RbNO3 + BeF2 yields Be(NO3)2 + 2RbF

2Rb+ + NO3- + Be^2+ + 2F- → Be(NO₃)₂ + 2RbF

This is correct

B. CaCl + LiCO3 yields CaCO3 + LiCl

This is not correct

The correct equation is:

CaCl2 + Li2CO3  → Ca2+ + 2Cl- + 2Li+ + CO3^2-  → 2LiCl + CaCO3

C. Na3PO4 + 3KOH yields 3NaOH + K3PO4

3Na+ + PO4^3- + 3K+ + 3OH- → 3NaOH + K3PO4

This is correct

D. 2MgI2 + Mn(SO3)2 yields 2MgSO3 + MnI4

2Mg^2+ + 4I- + Mn^4+ + 2SO3^2- → 2 MgSO3 + MnI4

This is correct

pla·gia·rism

/ˈplājəˌrizəm/

learn to pronounce

noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

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.