Beta decay occurs in two forms: β⁻ decay and β⁺ decay. In β⁻ decay, a neutron is transformed into a proton through the emission of an electron. If β⁻ decay occurs, the mass number of the daughter nucleus remains unchanged, but the number of protons increases by 1 and the number of neutrons decreases by 1, compared to the parent nucleus. On the other hand, β⁺ decay involves the conversion of a proton into a neutron via the emission of a positron. In this case, the mass number of the daughter nucleus stays the same, while the number of protons decreases by 1 and the number of neutrons increases by 1 compared to the parent nucleus.
Answer:
B
Explanation:
Flammable substances contain chemicals that react with flames, thus making it their chemical property, particularly when they encounter other materials that cause a reaction.
Answer: second option: 1.70 to 1.40
Explanation:
1) pH is defined using the formula pH = - log [H₃O⁺]
2) Given that the initial concentration is x and after doubling it becomes 2x, we calculate:
pHi = - logx
pHf = - log 2x = - log 2 - logx
Thus, pHf - pHi = - log2 - logx - (- logx) = - log2 ≈ - 0.30
⇒ pHi - pHf = 0.30, indicating that the final pH (with twice the hydronium ions) is 0.30 lower than the starting pH.
3) The only option that indicates a 0.30 decline in pH is the second one: from 1.70 to 1.40. Therefore, that is the correct choice.
In the reaction: <span>caco3(s) → cao(s) + co2(g), it is evident that
1 mol (which is 100 g) of CaCO3 yields 1 mol (which is 44 g) of CO2
Now, the molarity of CaCO3 present in the reaction system is
</span>=
=
= 0.45 mol
Thus, 0.45 mol of CaCO3 leads to the formation of 0.45 mol of CO2.
According to the ideal gas equation, we have PV = nRT
V =
.
Considering P = 645 torr = 0.8487 atm (because 1 atm = 760 torr)
In that case, V =
= 34.8 l
To find the temperature at which the volume of the gas would be 0.550 L, given that it is 0.432 L at -20.0 °C, apply Charles’s Law.
The formula is v1/T1 = v2/T2
Known values:
V1 = 0.550 L
T1 = ?
T2 = -20°C + 273 = 253 K
V2 = 0.432 L
Rearranging for T1:
T1 = (V1 × T2) / V2
Calculating:
T1 = (0.55 L × 253) / 0.432 L = 322.11 K or 49.11°C
