Answer: Melatonin has been used safely for up to 2 years in some people. However, it can cause some side effects including headache, short-term feelings of depression, daytime sleepiness, dizziness, stomach cramps, and irritability. Do not drive or use machinery for four to five hours after taking melatonin.
A)→ Haze surrounding a nucleus
B)→ Created by solar wind.
C)→ Hypothetical sphere around the solar system
The correct answer is A. All electrons become free and separate from the nuclei. In metallic bonds, the electrons of the metal atoms are delocalized. The electron in the electron sea can freely roam around or are free to flow.
Answer:
d. 1600 calories
Explanation:
The heat of fusion of water, L, is the amount of heat per gram required to melt the ice to water, a process which takes place at a constant temperature of 0 °C. The specific heat of water, c, is the amount of heat required to change the temperature of 1 gram of water by 1 degree Celsius.
We will convert the units of c from Jg⁻¹°C⁻¹ to cal·g⁻¹°C⁻¹ since the answers are provided in calories. The conversion factor is 4.18 J/cal.
(4.18 Jg⁻¹°C⁻¹)(cal/4.18J) = 1 cal·g⁻¹°C⁻¹
First we calculate the heat required to melt the ice, where M is the mass:
Q = ML = (15 g)(80 cal/g) = 1200 cal
Then, we calculate the heat required to raise the temperature of water from 0 °C to 25 °C.
Q = mcΔt = (15 g)(1 cal·g⁻¹°C⁻¹)(25 °C - 0 °C) = 380 cal
The answer is rounded so that there are two significant figures
The total heat required for this process is (1200 cal + 380 cal) = 1580 cal
The rounded answer is 1600 calories.
