Answer : Normally in any chemical reaction, if the enthalpy change i.e. ΔH is positive which means it is greater than zero then it can be called as an Endothermic Reaction.
Whereas, the system under study is absorbing heat that is produced during the reaction. So if ΔH is found to be positive then it can be called as endothermic reaction.
Answer:
A. It formed by barium(Ba+2) ion and sulfate ( SO42- )
B. It is formed by calcium ion (Ca+2) and two fluoride ions (2F-)
C. It is formed by magnesium ion (Mg+2) and nitride ion (N3-)
D. It is formed by two potassium ions (2 K+) and oxide ion(O2-)
Answer:
1.00 × 10¹⁸
Explanation:
1. Calculate the <em>energy of one photon</em>
The formula for the energy of a photon is
<em>E</em> = <em>hc</em>/λ
<em>h</em> = 6.626 × 10⁻³⁴ J·s; <em>c</em> = 2.998 × 10⁸ m·s⁻¹
λ = 477 nm = 477 × 10⁻⁹ m Insert the values
<em>E</em> = (6.626 × 10⁻³⁴ × 2.998× 10⁸)/(477 × 10⁻⁹)
<em>E</em> = 4.165× 10⁻¹⁹ J
2. Calculate the <em>number of photons</em>
Divide the total energy by the energy of one photon.
No. of photons = 0.418 × 1/4.165 × 10⁻¹⁹
No. of photons = 1.00 × 10¹⁸
<span><span>Atomic number36,</span><span>Atomic mass<span>83.80 g.mol -1,</span></span><span>Density<span>3.73 10-3 g.cm-3 at 20°C,</span></span><span>Melting point- 157 °C,</span><span>Boiling point<span>- 153° C</span></span></span>
