Answer:
This question is incomplete and unclear; the complete question including the missing part is:
Emelie is working on a science project. Her task is to answer the question:
"Does Rogooti (a hair cream sold on TV) affect the speed of hair growth
(in length)". Her family is willing to volunteer for the experiment. Identify the control group (CG) and the independent and dependent variables.
ANSWER:
Independent variable: Rogooti hair cream
Dependent variable: Speed of hair growth/length
Control group: Family members that do not use the Rogooti hair cream
Explanation:
In an experiment, the independent variable is the variable that the experimenter changes or manipulates in order to bring about a measurable response. In this case, the ROGOOTI HAIR CREAM is the independent variable.
Dependent variable refers to the variable that is measured or the variable that responds to the change made to the independent variable. In this case, the dependent variable is SPEED AT WHICH HAIR GROWS (IN LENGTH).
Control group in an experiment is the group that does not receive the experimental treatment. In this case, the experimental treatment is the Rogooti hair cream, hence, the control group will be the VOLUNTEER FAMILY MEMBERS THAT DOES NOT RECEIVE THE ROGOOTI HAIR CREAM ON THEIR HAIR.
Answer:
19,26 kJ
Explanation:
The work done when a gas expand with a constant atmospheric pressure is:
W = PΔV
Where P is pressure and ΔV is the change in volume of gas.
Assuming the initial volume is 0, the reaction of 500g of Zn with H⁺ (Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g)) produce:
500,0g Zn(s)×
×
= 7,648 moles of H₂
At 1,00atm and 303,15K (30°C), the volume of these moles of gas is:
V = nRT/P
V = 7,648mol×0,082atmL/molK×303,15K / 1,00atm
V = 190,1L
That means that ΔV is:
190,1L - 0L = <em>190,1L</em>
And the work done is:
W = 1atm×190,1L = 190,1atmL.
In joules:
190,1 atmL×
= <em>19,26 kJ</em>
I hope it helps!
Answer:
1 electron is involved.
Explanation:
Hello,
In redox reactions, when therer's the necessity to know the involved equivalents, they equal the number of transferred electrons, in this case, since one equivalent is stated, one electron is transferred (involved).
Best regards.
Answer:
- <em>The minimum number of photons that can be detected by the human eye is </em><u><em>6.03 × 10 ¹⁶</em></u><em> photons.</em>
Explanation:
The energy of one photon of light is related to the wavelength by the equation:
Where, E is the energy of one photon, h is the Planck's constant, c is the speed of light, and λ is the wavelength of the light.
You are given with <em>λ = 510 nm</em> (nanometers), which you must convert to m (meters), to use SI units ⇒ λ = 510 × 10⁻⁹ m.
The <em>physical constansts </em>needed are:
- Planck's constant, h = 6.63 × 10⁻³⁴ J.s
- Speed of light, in vacuum, c = 3.0 × 10⁻⁸ m/s
Now you can substitute in the formula can compute for the value of E:
- E = 6.63×10⁻³⁴ J.s × 3.0 × 10⁻⁸ m/s / (510×10⁻⁹ m) = 0.039 × 10⁻³³ J
Since, that is the energy of one photon of green light, to calculate the number of photons that can be detected by the human eye, you need to divide the amounf of <em>energy the human eye is able to detect, 2.35 × 10⁻¹⁸ J , </em>by the energy of a photon:
- number of photons = 2.35×10 ⁻¹⁸J / 0.039 × 10⁻³³ J/ photon
- number of photons = 60.3 × 10¹⁵ photons = 6.03 × 10¹⁶photons
