Q4. Oil rigs are used to drill for crude oil.a. Drill heads are made from steel. Steel is an alloy.
Explain why Alloys are harder than pure metals.

b. Drill heads also contain diamonds.
Describe as fully as you can the structure and bonding in diamond.

c. Polymers are produced from crude oil.
Describe the structure and bonding in thermosoftening polymer and explain why thermosoftening polymers melt when heated.

The first law of thermodynamics states ΔU = q + w, where ΔU is the change in internal energy of a system, q is the heat entering or leaving the system (positive if it is entering the system, negative if it is leaving), and w is work done by the system or on the system (positive if work is being done on the system, negative if the system is doing work on its surroundings).

(a) The problem gives us the change in internal energy, ΔU, -1.65 kJ, as well as change in heat, -1.87 kJ (notice the negative, heat is leaving the system into the surroundings).

Therefore our equation is ΔU = q + p = -1.65 = -1.87 + w.

Solving for w gives us 0.22 kJ.

(b) As stated before, work positive if work is being done on the system and negative if the system is doing work on its surroundings since it represents energy in the form of work in the system. Doing work will transfer that energy out of the system making the sign negative, and having work done on the system transfers that energy into the system, making the sign positive.

Since the sign of 0.22 is positive, that means work is being done on the system by its surroundings. This means the volume of the gas will decrease. If work were negative, the volume would increase.

Photosynthesis is the process in plants to make their food. This involves the use carbon dioxide to react with water and make sugar or glucose as the main product and oxygen as a by-product. I think the best answer would be the first statement.

Answer: Option A

Explanation:

Photosynthesis is a process that helps the plants to make food by the help of carbon dioxide from the atmosphere and water, nutrients from soil and converts it into glucose in the presence of sunlight.

Atmosphere is a non living component of environment where carbon dioxide is present and it is transferred to plants which is a living component of ecosystem.

Answer:

A free body diagram is used to calculate static and dynamic forces acting on an object. In other words, a free body diagram is the starting point to develop a mathematical model to find and calculate various forces acting on a body.

Explanation:

Answer:

d = 0.2 g/cm³

General Formulas and Concepts:

Density = mass / volume

Explanation:

Step 1: Define

m = 100 g

V = 500 cm³

d = ?

Step 2: Find density

1. Substitute:                              d = 100 g/500 cm³
2. Evaluate:                                 d = 1/5 g/cm³
3. Evaluate:                                 d = 0.2 g/cm³