Which of the following elements has two valence electrons? a. Sr b. Na c. Al d. B

The energy stored in foods and fuels is?

elixir [45]

Chemical potential energy

5 0

4 years ago

HEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEELLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP MEEEEEEEEEEEEEEEE

Ghella [55]

Answer:

I would say C

Explanation: Hope this helped

4 0

3 years ago

Read 2 more answers

a radioisotope has a half life of three hours how much of a 120g sample remains after 9 hours. what will the g amount be after 3

aksik [14]

$\huge\boxed{♔︎Answer♔︎}$

60g after 3 hours, 30g after 6 hours and 15g after 9 hours

Explanation:

Weight of the radioactive sample = 120g

half life time period = 3 hours

(a) The weight of sample after 3 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{3}{3} = 1$

The fraction of sample left

$\sf { \frac{1}{2} }^{1} = \frac{1}{2}$

Mass of the sample left

$\sf \frac{1}{2} \times 120 = \cancel\frac{120}{2} = 60g$

60g of sample is left after 3 hours

(b) The weight of sample after 6 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{6}{3} = 2$

The fraction of the sample left

$\sf { \frac{1}{2} }^{2} = \frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$

Mass of the sample left

$\sf \frac{1}{4} \times 120 = \cancel\frac{120}{4} = 30g$

30g of sample is left after 6 hours

(c) The weight of sample after 9 hours

$\textsf {No. of half lives} = \sf \cancel\frac{9}{3} = 3$

The fraction of sample left

$\sf { \frac{1}{2} }^{3} = \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{8}$

Mass of sample left

$\sf \frac{1}{8} \times 120 = \cancel \frac{120}{8} = 15g$

15g of sample is left after 9 hours.

3 0

2 years ago

Two scientists wrote a paper detailing their research and conclusions and submitted it to a scientific journal. Several months l

avanturin [10]

Two scientists wrote a paper detailing their research and conclusions and submitted it to a scientific journal. Several months later, they received the paper back from the publisher with many comments attached from several fellow scientists. It is either that they revise their study or replicate the study. Most scientists would revisit their work and the findings they had from their research. Most probable if they were successful and the comments of the publisher and the co-scientists were positive they could replicate the study to validate its accountability.

7 0

4 years ago

Which elements are gases at STP?

Gwar [14]

Answer:

hydrogen (H), nitogen (N), oxygen (O), fluorine (F), chlorine (Cl), helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn)

Explanation: found this online, it's best to remember them.

7 0

3 years ago