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goldfiish [28.3K]

4 years ago

15

How was it first discovered that hot air could rise?

1 answer:

Sunny_sXe [5.5K]4 years ago

6 0

The history of balloon flight dates to 1783, when two French brothers, Joseph and Etienne Montgolfier, discovered that filling a bag with hot air would cause it to rise. They demonstrated their principle at Annonay, France, on June 4, 1783, with an unmanned balloon made of linen and pape

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In nature, oxygen has three common isotopes. The atomic masses and relative abundances of these isotopes are given in the table

Vaselesa [24]

Answer: The average atomic mass of oxygen is 15.999 amu

Explanation:

Mass of isotope O-16 = 15.995 amu

% abundance of isotope O-16= 99.759 % = $\frac{99.759}{100}=0.99759$

Mass of isotope O-17 = 16.995 amu

% abundance of isotope O-17 = 0.037% = $\frac{0.037}{100}=0.00037$

Mass of isotope O-18 = 17.999 amu

% abundance of isotope O-18 = 0.204% = $\frac{0.204}{100}=0.00204$

Formula used for average atomic mass of an element :

$\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})$

$A=\sum[(15.995\times 0.99759)+(16.995\times 0.00037)+(17.999 \times 0.00204)]$

$A=15.999$

Thus the average atomic mass of oxygen is 15.999 amu

5 0

3 years ago

During which phase of mitosis does the cell begin to split into two daughter cells

artcher [175]

Answer:

$\text{Telophase}$

Explanation:

<em>Telophase is the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.</em>

<em />

<em /> $-TheAnimeGirl-$ <em />

3 0

2 years ago

Read 2 more answers

A system that does no work but that transfers heat to the surroundings has

ASHA 777 [7]

Answer:

answer is attached by me

Explanation:

hope it helps you

7 0

3 years ago

An ideal gas originally at 0.85 atm and 66°C was allowed to expand until its final volume, pressure and temperature were 94.0mL,

xeze [42]

Answer: The original volume in liters was 0.0707L

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1$ = initial pressure of gas = 0.85 atm

$P_2$ = final pressure of gas = 456 mm Hg = 0.60 atm (760mmHg=1atm)

$V_1$ = initial volume of gas = ?

$V_2$ = final volume of gas = 94.0 ml

$T_1$ = initial temperature of gas = $66^oC=273+66=339K$

$T_2$ = final temperature of gas = $113^oF=318K$ $(32^0F=273K)$

Now put all the given values in the above equation, we get:

$\frac{0.85\times V_1}{339}=\frac{0.60\times 94.0}{318}$

$V_1=70.7ml=0.0707L$ (1L=1000ml)

Thus the original volume in liters was 0.0707L

8 0

3 years ago

The correct coefficients needed to balance the following reaction are:

velikii [3]

I think the correct answer is c if not it’s d

5 0

3 years ago