Answer:
a) Step 1:

Step 2:

b) The overall balanced reaction for given process is ;

Explanation:
a)
Galena = 
Lead(II) oxide = 
Sulfur dioxide = 
Step 1:
Roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide.
Balanced equation of step 1:
..[1]
Step 2:
Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide.
Balanced equation of step 2:
..[2]
b)
For over all reaction add [1] and [2]. The overall balanced reaction for given process is ;

Answer:
Significant Figures
Explanation:
1) Annotation category: ...
2)RULES FOR SIGNIFICANT FIGURES.
3) All non-zero numbers ARE significant. ...
4)Zeros between two non-zero digits ARE significant. ...
5)Leading zeros are NOT significant. ...
6)Trailing zeros to the right of the decimal ARE significant. ...
7)Trailing zeros in a whole number with the decimal shown ARE significant. 8) to make you happy :) hope this helps you :)
Explanation:
Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.
The dry ice absorbs heat from the air in the flask and become CO2 gas directly. So the heat flow from air to dry ice. And the CO2 gas increase the amount of the air. Though the temperature decreases, the balloon still inflates.
1. Friction
2.conduction
3.induction
4. Conduction