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pickupchik [31]
3 years ago
9

In a controlled scientific experiment, a scientist A. alters one test variable (independent variable) and observes the effects o

n other test variables (independent variables). B. alters one outcome variable (dependent variable) and observes the effects on other outcome variable (dependent variables). C. alters the test variable (independent variable) and observes the effects on the outcome variable (dependent variable).
Chemistry
1 answer:
Lubov Fominskaja [6]3 years ago
6 0

Answer:

C )

Explanation:

Controlled scientific experiment tests scientific assumption (hypothesis), under controlled conditions.

In controlled scientific experiment, alters the test variable (independent variable) and observes the effects on the outcome variable (dependent variable).

Eg : Studying impact of sunlight on plant's group, where former independent variable is altered & its effects on dependent outcome variable is observed.

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This is the chemical formula for nickel tetracarbonyl (a powerfully poisonous liquid used in nickel refining):nico4a chemical en
lesya [120]

Answer : There are 7.0 moles of oxygen in the formula.

Explanation :

The chemical formula of nickel tetracarbonyl is Ni(CO)₄.

We can see that there are 4 carbon atoms and 4 oxygen atoms which together form 4 carbonyl (CO) groups.

Therefore the mole ratio of C to O is 1 : 1.

Let us use this as a conversion factor to find moles of oxygen.

We have 7.0 moles of carbon in the formula.

The moles of O can be calculated as,

7 mol C \times \frac{1 mol O}{1 mol C} = 7.0 mol O

There are 7.0 moles of oxygen in the formula.

8 0
3 years ago
Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe. The mass of a helium−4 a
dmitriy555 [2]

<u>Answer:</u> The fraction of atom's mass contributed by nucleus is 0.99

<u>Explanation:</u>

Nucleons are defined as the sub-atomic particles which are present in the nucleus of an atom. Nucleons are protons and neutrons.

The isotopic symbol of Helium-4 atom is _2^4\textrm{He}

Number of electrons = 2

Number of protons = 2

Number of neutrons = 4 - 2 = 2

We are given:

Mass of He-4 atom = 6.64648\times 10^{-24}g

Mass of 1 electron = 9.10939\times 10^{-28}g

Calculating the mass contributed by the nucleus = m_{He}-2(m_e)

Mass of the nucleus of He-4 atom = 6.64648\times 10^{-24}-(2\times (9.10939\times 10^{-28}))=(6.64648-0.0018219)\times 10^{-24}=6.64466\times 10^{-24}

To calculate the fraction of atom's mass contributed by the nucleus, we use the equation:

\text{Fraction of atom's mass contributed by nucleus}=\frac{\text{Mass of nucleus}}{\text{Mass of atom}}

Putting values in above equation, we get:

\text{Fraction of atom's mass contributed by nucleus}=\frac{6.64466\times 10^{-24}g}{6.64648\times 10^{-24}g}=0.99

Hence, the fraction of atom's mass contributed by nucleus is 0.99

8 0
3 years ago
A solution is prepared by dissolving 0.5636 g oxalic acid (H2C2O4) in enough water to make 100.0 mL of solution. A 10.00-mL aliq
zepelin [54]

Answer:

The final molarity of the diluted oxalic acid solution is 0.002504 M

Explanation:

Step 1: Data given

Mass of oxalic acid (H2C2O4) = 0.5636 grams

Volume of the solution = 100.0 mL = 0.100 L

A 10 ml of this solution diluted in 250 ml of solution.

Molecular weight of H2C2O4  = 90.03 g/mol

Step 2: Calculate  initial moles of H2C2O4

Moles H2C2O4  = mass / molar mass

Moles H2C2O4  = 0.5636 grams / 90.03 g/mol

Moles H2C2O4 = 0.00626 moles

Step 3: Calculate molarity of the solution

Molarity = moles / volume

Molarity = 0.00626 moles / 0.100 L

Molarity = 0.0626 M

Step 4: Calculate moles of a 10.00 mL aliquot

Moles = 0.0626 M * 0.010 L

Moles = 0.000626 moles

Step 5: Calculate the new molarity

Molarity = 0.000626 moles / 0.250 L

Molarity = 0.002504 M

The final molarity of the diluted oxalic acid solution is 0.002504 M

6 0
3 years ago
ANSWER THESE 5 MULTPLE CHOICE QUESTIONS!!!<br> I'LL GIVE 30 POINTS AND A BRAINIEST:)
mestny [16]

Answer: 1, magnesium & mg

2, two energy shells

Explanation:

3 0
2 years ago
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Is air homogeneous or heterogeneous?
ivolga24 [154]

Answer:  yes, Air is a homogeneous mixture of the gaseous substances nitrogen, oxygen, and smaller amounts of other substances. Salt, sugar, and substances dissolve in water to form homogeneous mixtures. A homogeneous mixture in which there is both a solute and solvent present is also a solution

Explanation:

8 0
2 years ago
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