Protists belong to the group eukaryotes (having their DNA enclosed inside the nucleus). They are not plants, animals or fungi but they act like one. They can be in general subgroups such as unicellular algae, protozoa and molds.
This is an example of negative mutation. Negative mutations produce a phenotype that acts antagonistically to the wild-type phenotype. On the other hand positive mutation produce a phenotype that acts synergistically to the wild-type phenotype.
The negative mutation will negatively affect the long term survival of the butterfly species as the mutation makes the new butterfly offsprings more visible to predators.
The time taken for the croissant to hit you on the head assuming you are 1.5 m tall is 7.73 s
Considering the question given above, your height was not stated.
Thus, the height of the Eiffel Tower to your head will be:
Total height of tower = 300.5 m
Your assumed height = 1.5 m
Height (h) = 300.5 – 1.5
Finally, we shall determine the time taken for the croissant to hit you on the head.
Height (h) = 299 m
Acceleration due to gravity (g) = 10 m/s²
H = ½gt²
299 = ½ × 10 × t²
299 = 5 × t²
Divide both side by 5
Take the square root of both side
Therefore, the time taken for the croissant to hit you on the head assuming you are 1.5 m tall is 7.73 s
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Answer:
228
Explanation:
alpha decay is removing alpha particle
2 number of protons, 4 mass number = 2 protons + 2 neutrons
We have
90 protons and 142 neutrons
- 2 protons - 2 neutrons
88 protons 140 neutrons
Mass number of new (daughter) atom = 88 +140 = 228
Answer:
Correct Answer: 228
Explanation:
alpha decay is removing alpha particle
2 number of protons, 4 mass number = 2 protons + 2 neutrons
________________________________________________
We have:
_______________________
90 protons and 142 neutrons
- 2 protons - 2 neutrons
88 protons 140 neutrons
Mass number of new (daughter) atom = 88 +140 = 228
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Answer:
0.22 grams of magnesium
This seems too low, so check the calculations/
Explanation:
How is the heat delivered? Is the magnesium hot and added to the water? If so, at what temperature.
Is the heat generated from an exothermic chemical reaction?
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I'll assume here that the heat comes from the reaction of magnesium with water. The balanced equation is:
Mg + 2H2O = Mg(OH)2 + H2
It has a heat of reaction of −924.7 kJ/mol.
We need enough Mg to heat 30 ml of water from 22°C to 90°C. The specific heat of water is needed. It is 4.184 J/g-K. It tells us that 4.184 Joules are needed to raise the temperature of water by 1 degree K.
30 ml of water with density 1 gram/ml means we have 30 grams of water. (We'll ignore the water that is added from the chemical reaction.).
Lets calculate the Joules required to raise 30 grams of water from 22°C to 90°C. Note that the specific heat has units of g and Kelvin. Since we need a temperature change, the number value for ΔT is the same for both °C and °K. So the temperature change is +68°K.
We can now calculate the Joules required:
(30 grams H2O)*(4.184 J/g-K)*(+68°K) = 8535.4 Joules or 8.5 kJ to 2 sig figs.
The Mg/H2O heat of reaction of −924.7 kJ/mol. will allow us to calculate the amount of Mg needed to supply 8.5 kJ. The minus sign tells us that the reaction RELEASES energy (the energy leaves the "system" of Mg and H2O).
Calculate the moles of Mg needed to release 8.5 kJ:
(924.7 kJ/mole)*(x moles) = 8.5 kJ
x moles = 0.0092 moles
Whoa. That is only (0.0092 moles)*(24.03 g/mole) = 0.22 grams of magnesium
This seems low to me, so check on the heat of reaction figure I used. And don't let the hydrogen get away.