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4 years ago

Sand dollars are radially symmetrical and have an internal skeleton but no backbone. Which phylum do sand dollars belong in?

Chemistry

2 answers:

notsponge [240]4 years ago

5 1

Answer:

Echinoderms

Explanation:

Because i'm right

Law Incorporation [45]4 years ago

4 0

Answer and Explanation,

Sand dollar, any of the invertebrate marine animals of the order Clypeastroida (class Echinoidea, phylum Echinodermata) that has a flat, disk-shaped body. They are close relatives of sea urchins and heart urchins. The sand dollar is particularly well adapted for burrowing in sandy substrates. Very small spines used for digging and crawling cover the entire surface of its body and are appressed backwards toward the posterior anus. The mouth is located in the centre of the body’s underside. The upper surface exhibits pentaradiate symmetry, with a pattern of five “petals” spreading out from the centre. Some species found stranded on the shores of North America have five or six slots, or lunules, through the test (external skeleton). Most sand dollars measure from 5 to 10 cm (2 to 4 inches) in diameter. Species of comparable size occur in shallow coastal waters throughout the rest of the world, except in Europe and Antarctica.

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If you answer and explain I will give 25 points!

snow_tiger [21]

Answer:535.5g

Explanation:

1) find the volume of the object

=L*W*H

=1.8*3.5*10.0

=63cm^3

2) the original formula is solving for the dencity which we have so...

D=M/V

M=D*V

M=8.5(63)

M=535.5g

7 0

3 years ago

A sample of ammonia reacts with oxygen as shown. 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) What is the limiting reactant if 4.0 g of NH3

antiseptic1488 [7]

Ans: O2 because it produces only 0.20 mol of NO

Given:

Mass of NH3 = 4.0 g

Mass of O2 = 8.0 g

To determine:

The limiting reagent in the given reaction

4NH3 + 5O2 → 4NO + 6H2O

Explanation:

# moles of NH3 = 4.0/17 g.mol-1 = 0.2353 moles

# moles of O2 = 8.0/32 = 0.25 moles

Based on the reaction stoichiometry:

1 mole of NH3 produces 1 mole of NO

Therefore, 0.2353 moles of NH3 will produce: 0.2353 moles of NO

Similarly, 1 mole of O2 will produce 4/5 moles of NO

0.25 moles of O2 will form: 0.25*4/5 = 0.2 moles of NO

Thus, O2 is the limiting reactant.

4 0

4 years ago

Read 2 more answers

Caffeine is a compound found in some natural coffees and teas and in some colas. a. Determine the empirical formula for caffeine

andrey2020 [161]

Answer: The molecular formula will be $C_8N_4H_{10}O_2$

Explanation:

Mass of C= 49.47 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Mass of H = 5.20 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.47g}{12g/mole}=4.12moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.20g}{1g/mole}=5.20moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{4.12}{1.03}=4$

For N = $\frac{2.06}{1.03}=2$

For O = $\frac{1.03}{1.03}=1$

For H = $\frac{5.20}{1.03}=5$

The ratio of C : N: O: H = 4: 2: 1: 5

Hence the empirical formula is $C_4N_2OH_5$

The empirical weight of $C_4N_2OH_5$ = 4(12)+2(14)+1(16)+5(1)= 97 g.

The molecular weight = 194.19 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight}}{\text{Equivalent weight}}=\frac{194.19}{97}=2$

The molecular formula will be = $2\times C_4N_2H_5O=C_8N_4H_{10}O_2$

5 0

3 years ago

Balance the following equations. Do not include the states of matter. (a) C + O2 → CO

krek1111 [17]

Answer:

C + O2 → CO2

Explanation:

C + O2 → CO ----------------- (1)

from equ (1) on reactant side, C has 1 mole, O has 2 moles

from equ (1) on product side, C has 1 mole, O has 1 mole

Thus, to balance the equation, O should have 2 moles

C + O2 → CO2

7 0

3 years ago

Read 2 more answers

What is a saturated solution? A. A solution containing more solute than should be possible. B. A solution that can still dissolv

LUCKY_DIMON [66]

Answer:

C. A solution that cannot dissolve any more solute.

Explanation:

hope it helps .

6 0

4 years ago