2. Solid sodium reacts with gaseous chlorine to produce sodium chloride.

If the half life of iridium-182 is 15 years, how much of a 3 gram sample is left after 2 half-lives?

padilas [110]

Answer:

D. 0.75 grams

Explanation:

The data given on the iridium 182 are;

The half life of the iridium 182, $t_{(1/2)}$ = 15 years

The mass of the sample of iridium, N₀ = 3 grams

The amount left, N(t) after two half lives is given as follows;

$N(t) = N_0 \left (\dfrac{1}{2} \right )^{\dfrac{t}{t_{1/2}} }$

For two half lives, t = 2 × $t_{(1/2)}$

∴ t = 2 × 15 = 30

$\dfrac{t}{t_{(1/2)}} = \dfrac{30}{15} = 2$

$\therefore N(t) = 3 \times\left (\dfrac{1}{2} \right )^2 = 0.75$

∴ The amount left, N(t) = 0.75 grams

4 0

3 years ago

If a stone with an original velocity of 0 is falling from a ledge and takes 8 seconds to hit the ground what is the final veloci

ziro4ka [17]

Also 0 as it hits the ground and stops

5 0

3 years ago

The secondary structure of a protein is distinct from the tertiary structure of a protein mainly because the secondary structure

mixer [17]

Answer:

False

Explanation:

The primary structure of a protein refer to the amino acid sequence. The secondary structure of a protein refer to the alpha helices, beta sheets and turns, while the tertiary structure refer to folding of the sheets due to hydrogen bonding or other bonding interaction between them.

4 0

3 years ago

A piece of material with a mass of 755 g is heated to 84.5 c and added to 50 g of water at 5

lana [24]

Alright sorry you're getting the answer hours later, but i can help with this.
so you're looking for specific heat, the equation for it is <span>macaΔTa = - mbcbΔTb with object a and object b. that's mass of a times specific heat of a times final minus initial temperature of a equals -(mass of b times specific heat of b times final minus initial temperature of b)
</span>so putting in your values is, 755g * ca * (75 celsius - 84.5 celsius) = -(50g * cb * (75 celsius - 5 celsius))
well we know the specific heat of water is always 4180J/kg celsius, so put that in for cb
with a bit of simplification to the equation by doing everything on each side first you have, -7172.5 * ca = -14630000
divide both sides by -7172.5 so you can single out ca and you get, ca= 2039.74
add units for specific heat which are J/kg celsius and the specific heat of the material is 2039.74 J/kg celsius

6 0

4 years ago

Zinc metal (Zn) will react with aqueous hydrochloric acid (HCI aq) to produce aqueous zinc chloride (ZnCl2 aq) and hydrogen gas

Debora [2.8K]

Answer: