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nika2105 [10]
3 years ago
10

Can someone help, please ??

Chemistry
2 answers:
Yuri [45]3 years ago
8 0
13. The periodic table was discovered by Dalton.
14.NaCl is sodium chloride
Zinaida [17]3 years ago
5 0
Number 13 is D. Mendeleev. He was a Russian chemist and inventor who formulated the periodic table.
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A 360. g iron rod is placed into 750.0 g of water at 22.5°C. The water temperature rises to 46.7°C. What was the initial tempera
Grace [21]

Answer: The initial temperature of the iron was 515^0C

Explanation:

heat_{absorbed}=heat_{released}

As we know that,  

Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})

m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]         .................(1)

where,

q = heat absorbed or released

m_1 = mass of iron = 360 g

m_2 = mass of water = 750 g

T_{final} = final temperature = 46.7^0C

T_1 = temperature of iron = ?

T_2 = temperature of water = 22.5^oC

c_1 = specific heat of iron = 0.450J/g^0C

c_2 = specific heat of water= 4.184J/g^0C

Now put all the given values in equation (1), we get

-360\times 0.450\times (46.7-x)=[750\times 4.184\times (46.7-22.5)]

T_i=515^0C

Therefore, the initial temperature of the iron was 515^0C

4 0
3 years ago
According to the quantum mechanical model of the atom, asking, "Where is the electron?" is not nearly as helpful as asking this
svetlana [45]

The correct answer is option B. Where are the regions of electron density?

In the quantum mechanical model of the atom the exact location of an electron is unknown. But there is a probability of finding an electron in a given space. So in quantum mechanics instead of an electron we always refer to electron density, which is simply the probability of finding an electron in space.



6 0
3 years ago
A piece of copper has a volume of 100.0cm^3 (3power) if the mass of the copper is 890g, what is the density of copper??
Bas_tet [7]
Density=mass/volume
Data:
mass=890 g
volume=100 cm³

Density=890 g/100 cm³=8.9 g/cm³

answer: the density of the copper is 8.9 g/cm³
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Electronic items contain lcds
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