An atom of oxygen has an atomic number of 8 and a mass number of 18. How many of each type of subatomic particle does it contain

Response:

D.

Justification:

The slight warm feeling noticed at the valve stem when air is pumped into the tire is likely due to the kinetic energy generated by the friction from the pump and the resultant increase in gas pressure within the tire.

The experimental setup involves assessing the temperature of the pizza, which serves as the dependent variable, after being allowed to cool in various thermal environments over a consistent time period used as a control. The following parameters are considered: The initial temperature of the pizza is 400°F, the freezer temperature is 0°F, the refrigerator is at 40°F, and the countertop is 78°F. The independent variable is the heat level experienced by the hot pizza, while the dependent one indicates the temperature it achieves during the cooling process. The plan for the experiment entails: 1) Positioning the pizza at 400°F in each heat setting (freezer, refrigerator, countertop) for the same duration, subsequently documenting the final temperature of the pizza. 2) The option yielding the lowest temperature after that timeframe indicates the fastest cooling method for the pizza.

Answer: C. 151 g

Solution: The balanced equation given is:

From this equation, the ratio of moles between all substances is 1:1. We have 117 grams of LIOH and 141 grams of HBr available and need to calculate the theoretical yield of LiBr.

We should convert each reactant’s grams into moles to identify the limiting reagent since the theoretical yield relies on it.

Molar mass for LiOH = 6.94 + 15.999 + 1.008 = 23.947 grams per mole

Molar mass for HBr = 1.008 + 79.904 = 80.912 grams per mole

To find the moles of each reactant, we divide their grams by their respective molar masses.

Moles of LiOH = = 4.89 mol

Moles of HBr = = 1.74 mol

As there are fewer moles of HBr, it is the limiting reactant. With a 1:1 mol ratio between HBr and LiBr, 1.74 moles of LiBr can be produced.

Molar mass of LiBr = 6.94 + 79.904 = 86.844 grams per mole

The mass of LiBr formed = = 151 g LiBr

Based on calculations, the theoretical yield of LiBr is 151 g, hence the correct answer is C.

Answer:

The proportion of the family's overall yearly electricity that is attributed to running both air conditioners over the summer months is = 19.4 %

Explanation:

Monthly average electricity usage = 900 kWh

The family utilizes two window air conditioners to cool their residence during summer for three months.

The electricity usage for a single window-unit air conditioner = 350 kWh

The total power utilized by both window-unit air conditioners = 350(2) = 700 kWh

The total power consumed by two air conditioners for the summer months = 700 (3) = 2100 kWh

The annual total power consumption = 900 (12) = 10800 kWh

The percentage of the family's total annual electricity for operating the air conditioners during summer = = 19.4 %