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jok3333 [9.3K]
3 years ago
15

Which step comes before conducting an experiment in the scientific method

Chemistry
2 answers:
Romashka-Z-Leto [24]3 years ago
7 0

Answer:

Making a hypothesis

Explanation:

tiny-mole [99]3 years ago
7 0
Answer : Observation/Question
You might be interested in
B. Why is this number called a "mass” number?
deff fn [24]

<u>Answer:</u>

The mass of the atom depends on the sub atomic particles present in the nucleus of an atom.

That is, the protons and the neutrons.

Electrons are present around the nucleus and the mass is negligible since its mass is very very less.

<em>mass of a proton = 1.673\times10^{-27} kg</em>

<em>mass of a neutron = 1.675 \times 10^{-27} kg</em>

<em>mass of an electron = 9.109 \times 10^{-31} kg</em>

Mass number represents the mass of one particular isotope and it is a whole number for example, _6 C^{13}

Mass number is 13 and atomic number is 6 for the carbon isotope C-13.  

Atomic mass is different from mass number and it is a fraction since it is the average atomic mass of all the isotopes of an atom.

Atomic mass of C is 12.011 amu which we see in the periodic table is the average atomic mass of isotopes C-12, C-13 and C-14.

7 0
3 years ago
The table compares some characteristics of two atoms.
Mademuasel [1]

Answer:

Explanation:

Atom X,

Neutron num = 4, Mass num = 7

Therefore, proton number = Mass num - Neutron num

                                           = 7 - 4

                                           = 3

Atom Y,

Neutron num = 5, Mass num = 9

Therefore, proton number = Mass num - Neutron num

                                           = 9 - 5

                                           = 4

1) False. Atom X belongs to group 3 while atom Y belongs to group 4

2) False. Atom X is in a column on the left of Atom Y

3) True. Atom X and atom Y belong to the same period two on the periodic table

4) Fasle. Atom X and Y are not isotopes because they do not have the same atomic number.

Isotopy is a phenomenon whereby atom of same element have same atomic number but different mass number

4 0
3 years ago
How many moles of calcium chloride (CaCl2) are needed to react completely with 6.2 moles of silver nitrate (AgNO3)? 2AgNO3 + CaC
nexus9112 [7]

Here we have to choose the right option which tells the moles of CaCl₂ will react with 6.2 moles of AgNO₃ in the reaction

2AgNO₃ + CaCl₂→ 2AgCl + Ca(NO₃)₂

6.2 moles of silver nitrate (AgNO₃) will react with B. 3.1 moles of calcium chloride (CaCl₂).

From the reaction: 2AgNO₃ + CaCl₂→ 2AgCl + Ca(NO₃)₂

Thus 2 moles of AgNO₃ reacts with 1 mole of CaCl₂

Henceforth, 6.2 moles of AgNO₃ reacts with \frac{6.2}{2} = 3.1 moles of CaCl₂.

1 mole of CaCl₂ reacts with 2 moles of AgNO₃. Thus-

A. 2.2 moles of CaCl₂ will react with 2.2×2 = 4.4 moles of AgNO₃.

C. 6.2 moles of CaCl₂ will reacts with 6.2×2 = 12.4 moles of AgNO₃.

D. 12.4 moles of CaCl₂ will reacts with 12.4 × 2 = 24.8 moles of AgNO₃

Thus the right answer is 6.2 moles of AgNO₃ will react with 3.1 moles of CaCl₂.

6 0
3 years ago
How much energy must be removed from a 94.4 g sample of benzene (molar mass= 78.11 g/mol) at 322.0 K to solidify the sample and
Kay [80]

Answer : The energy removed must be, 29.4 kJ

Explanation :

The process involved in this problem are :

(1):C_6H_6(l)(322K)\rightarrow C_6H_6(l)(279K)\\\\(2):C_6H_6(l)(279K)\rightarrow C_6H_6(s)(279K)\\\\(3):C_6H_6(s)(279K)\rightarrow C_6H_6(s)(205K)

The expression used will be:  

Q=[m\times c_{p,l}\times (T_{final}-T_{initial})]+[m\times \Delta H_{fusion}]+[m\times c_{p,s}\times (T_{final}-T_{initial})]

where,

Q = heat released for the reaction = ?

m = mass of benzene = 94.4 g

c_{p,s} = specific heat of solid benzene = 1.51J/g^oC=1.51J/g.K

c_{p,l} = specific heat of liquid benzene = 1.73J/g^oC=1.73J/g.K

\Delta H_{fusion} = enthalpy change for fusion = -9.8kJ/mol=-\frac{9.8\times 1000J/mol}{78g/mol}=-125.6J/g

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

Q=[94.4g\times 1.73J/g.K\times (279-322)K]+[94.4g\times -125.6J/g]+[94.4g\times 1.51J/g.K\times (205-279)K]

Q=-29427.312J=-29.4kJ

Negative sign indicates that the heat is removed from the system.

Therefore, the energy removed must be, 29.4 kJ

3 0
3 years ago
How does prairie grasses protect soil
jeyben [28]

Prarie Grass Protects soil ( And this is just what I think, so I am sorry if I am wrong)

But I think that the grass is there so that the dirt doesn't fly away.

4 0
3 years ago
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