Question
Chemical equations must be balanced because
a
mass can neither be created nor destroyed.
b
the mass of the products is always greater than the mass of the reactants.
c
the mass of the reactants is always greater than the mass of the products.
d
mass is determined by a chemical reaction.
a
mass can neither be created nor destroyed.
b
the mass of the products is always greater than the mass of the reactants.
c
the mass of the reactants is always greater than the mass of the products.
d
mass is determined by a chemical reaction.
Answers
GPT-4o mini
The correct answer is:
**a. mass can neither be created nor destroyed.**
This fundamental principle, known as the law of conservation of mass, states that in a closed system, the total mass of the reactants must equal the total mass of the products in a chemical reaction. Therefore, chemical equations must be balanced to reflect this conservation.
**a. mass can neither be created nor destroyed.**
This fundamental principle, known as the law of conservation of mass, states that in a closed system, the total mass of the reactants must equal the total mass of the products in a chemical reaction. Therefore, chemical equations must be balanced to reflect this conservation.
How many half-lives does it take a radioactive substance to decay until only one-eighth of the original substance remains?
a
six
b
eight
c
three
d
two
a
six
b
eight
c
three
d
two
GPT-4o mini
To determine how many half-lives it takes for a radioactive substance to decay to one-eighth of its original amount, we can use the following reasoning:
- After 1 half-life, \( \frac{1}{2} \) remains.
- After 2 half-lives, \( \frac{1}{4} \) remains.
- After 3 half-lives, \( \frac{1}{8} \) remains.
Thus, it takes **3 half-lives** for a radioactive substance to decay to one-eighth of its original amount.
The correct answer is:
**c. three**.
- After 1 half-life, \( \frac{1}{2} \) remains.
- After 2 half-lives, \( \frac{1}{4} \) remains.
- After 3 half-lives, \( \frac{1}{8} \) remains.
Thus, it takes **3 half-lives** for a radioactive substance to decay to one-eighth of its original amount.
The correct answer is:
**c. three**.
223/87 Fr arrow 0/-1 e + A/Z X
What is the atomic mass of the new atom?
What is the atomic number of the new atom?
What is the symbol of the new atom?
What type of decay is demonstrated here?
What is the atomic mass of the new atom?
What is the atomic number of the new atom?
What is the symbol of the new atom?
What type of decay is demonstrated here?
GPT-4o mini
The given nuclear reaction involves the decay of Francium-223 (\(^{223}_{87} \text{Fr}\)) by emitting a beta particle (\(^{0}_{-1} \text{e}\)).
Here's the breakdown of the decay process:
1. **Beta Decay**: In beta decay, a neutron in the nucleus decays into a proton and an electron (the beta particle). This process increases the atomic number by 1 while the atomic mass remains the same, because a neutron is converted into a proton.
2. **Calculating the Atomic Number and Mass of the New Atom**:
- **Original Atom (Fr)**:
- Atomic mass (A) = 223
- Atomic number (Z) = 87
- **After Beta Decay**:
- Atomic mass (remains unchanged) = 223
- Atomic number (Z increases by 1) = 87 + 1 = 88
3. **Identifying the New Atom**:
- The element with atomic number 88 is Radium, which has the symbol \(^{223}_{88} \text{Ra}\).
### Summary:
- **Atomic Mass of the New Atom**: 223
- **Atomic Number of the New Atom**: 88
- **Symbol of the New Atom**: \( \text{Ra} \) (for Radium)
- **Type of Decay**: Beta decay
Thus, the answer is:
- Atomic mass: 223
- Atomic number: 88
- Symbol: \( \text{Ra} \)
- Type of decay: Beta decay
Here's the breakdown of the decay process:
1. **Beta Decay**: In beta decay, a neutron in the nucleus decays into a proton and an electron (the beta particle). This process increases the atomic number by 1 while the atomic mass remains the same, because a neutron is converted into a proton.
2. **Calculating the Atomic Number and Mass of the New Atom**:
- **Original Atom (Fr)**:
- Atomic mass (A) = 223
- Atomic number (Z) = 87
- **After Beta Decay**:
- Atomic mass (remains unchanged) = 223
- Atomic number (Z increases by 1) = 87 + 1 = 88
3. **Identifying the New Atom**:
- The element with atomic number 88 is Radium, which has the symbol \(^{223}_{88} \text{Ra}\).
### Summary:
- **Atomic Mass of the New Atom**: 223
- **Atomic Number of the New Atom**: 88
- **Symbol of the New Atom**: \( \text{Ra} \) (for Radium)
- **Type of Decay**: Beta decay
Thus, the answer is:
- Atomic mass: 223
- Atomic number: 88
- Symbol: \( \text{Ra} \)
- Type of decay: Beta decay