Answer:
Q = 1.5 kJ
Explanation:
It is given that,
The specific heat for aluminum is 0.900 J/g°C
Mass of sample, m = 3.8 g
Initial temperature, ![T_i=450^{\circ} C](https://tex.z-dn.net/?f=T_i%3D450%5E%7B%5Ccirc%7D%20C)
Final temperature, ![T_f=25^{\circ} C](https://tex.z-dn.net/?f=T_f%3D25%5E%7B%5Ccirc%7D%20C)
We need to find the heat released. The amount of heat released is given by the formula:
![Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\Q=3.8\times 0.9\times (25-450)\\\\Q=1453.5\ J\\\\Q=1.45\ kJ](https://tex.z-dn.net/?f=Q%3Dmc%5CDelta%20T%5C%5C%5C%5CQ%3Dmc%28T_f-T_i%29%5C%5C%5C%5CQ%3D3.8%5Ctimes%200.9%5Ctimes%20%2825-450%29%5C%5C%5C%5CQ%3D1453.5%5C%20J%5C%5C%5C%5CQ%3D1.45%5C%20kJ)
or
![Q=1.5\ kJ](https://tex.z-dn.net/?f=Q%3D1.5%5C%20kJ)
So, the correct option is (A) i.e. 1.5 kJ.
We first determine the complete reaction of the substances given above to tell whether precipitates are formed.
NaCl + NaBr = no reaction
NaCl + Na2CO3 = no reaction
<span>NaCl + BaCl2 = no reaction</span>
<span>NaCl + HCl = no reaction
</span>
From all the substances given, reaction cannot happen therefore no precipitates are formed.
Answer: the electrons i.e their valence electron
Explanation: valence electron is the number of electron in the outermost shell of an atom. Infact it is the combining power of an element. The valence electron gives us a better understanding of how an element will react with other elements. This is the reason why elements with the same number of valence electron(s) are grouped together telling us that they exhibit similar chemical properties
<h3>
Answer:</h3>
4.227 × 10^-19 Joules
<h3>
Explanation:</h3>
Energy of a photon of light is calculated by the formula;
E = hf, where h is the plank's constant, 6.626 × 10^-34 J-s and f is the frequency.
But, f = c/λ
Where, c is the speed of light (2.998 × 10⁸ m/s), and λ is the wavelength.
Given the wavelength is 470 nm or 4.7 × 10^-7 m
Therefore;
E = hc/λ
= (6.626 × 10^-34 J-s × 2.998 × 10^8 m/s) ÷ 4.7 × 10^-7 m
= 4.227 × 10^-19 Joules
Therefore, the energy of a photon with 470 nm is 4.227 × 10^-19 Joules