Answer:
To regulate the gas pressure in the lighter tank and avoid build-up of pressure.
Explanation:
- First, you need to understand the properties of this organic molecule. Butane. C₄H₁₀ is a colorless, odorless, but HIGHLY FLAMMABLE liquefied gas. The liquid is flammable at 25⁰C whilst the vapor is flammable at 15⁰C. As you can see, this is an extremely flammable gas. It has a high vapor pressure (tendency by liquids to escape as gas molecules)
- Any external heat source induces a pressure build up that might cause the gas to explode when there is an open flame.
- Combining the two points above, a thermo-regulated water bath that has a lower temperature (below 15⁰C) will be need to prevent the pressure build up and ensure that any leakage will not have a high vapor pressure.
Answer: A. is elliptical
B. IS inrregulur C. spiral
Explanation: this should be it
The correct answer for the blanks is : Primary key field
The primary key field is a place to record data that is unique to each record in the database or file. When you perform your hide duplicate command on primary key field, it will prevent any records from having the same value
Answer:
Reaction A, B, E and F are exothermic reactions.
Explanation:
Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system.
The total enthalpy of the reaction 
comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system.
The total enthalpy of the reaction comes out to be positive.
So, from the given option reaction which are exothermic are with negative value that enthalpy of reaction and those are:
1) 
,ΔH = -1203 kJ/mol
2)
,ΔH =-176 kJ/mol
3) 
,ΔH = -393.5 kJ/mol
4) 
,ΔH =-891 kJ/mol
