The combustion of a hydrocarbon X (30 cm3) with 350 cm3 of oxygen at STP resulted in the formation of 440 cm3 of gaseous products. The volume of gases was reduced to 360 cm3 when the excess O2 was removed and then reduced by half when bubbled through NaOH.

To answer this question, let's break it down step by step.

Step 1: Calculate the volume of the products formed after combustion.
First, we know that the initial volume of hydrocarbon X is 30 cm3 and the volume of oxygen is 350 cm3. According to the given information, the volume of gaseous products obtained is 440 cm3. Therefore, the volume of the products can be calculated by subtracting the initial volume of the reactants from the total volume after the reaction:
Volume of products = Total volume - Initial volume of reactants
Volume of products = 440 cm3 - (30 cm3 + 350 cm3)
Volume of products = 60 cm3.

Step 2: Determine the volume of gases after removing the excess oxygen.
After the combustion, the gases are reduced to 360 cm3 by removing the excess oxygen. This means that the remaining gases after removing the excess oxygen have a volume of 360 cm3.

Step 3: Calculate the volume of gases after bubbling through NaOH.
The volume of the gases is reduced by half when bubbled through NaOH. Therefore, the volume of gases after bubbling through NaOH would be half of the previous volume, which is 360 cm3/2 = 180 cm3.

In summary:
- The volume of gaseous products formed after combustion is 60 cm3.
- The volume of gases after removing the excess oxygen is 360 cm3.
- The volume of gases after bubbling through NaOH is 180 cm3.

To find the balanced equation and identify the hydrocarbon X, we need to analyze the volumes of reactants and products.

Let's start by calculating the moles of oxygen used in the reaction:

Using the ideal gas law, we can relate the volume of a gas to its number of moles.

First, let's convert the volumes from cm3 to liters:

30 cm3 = 30/1000 = 0.03 L (volume of X)
350 cm3 = 350/1000 = 0.35 L (volume of O2)
440 cm3 = 440/1000 = 0.44 L (volume of products)
360 cm3 = 360/1000 = 0.36 L (volume of products without excess O2)
(1/2) * 0.36 L = 0.18 L (volume bubbled through NaOH)

Using the ideal gas law equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant (0.0821 L·atm/(mol·K)), and T is temperature (STP: 273 K), we can rearrange the equation to solve for n:

n = (PV) / (RT)

Let's calculate the moles of oxygen used in the reaction:

nO2 = (0.35 L * 1 atm) / (0.0821 L·atm/(mol·K) * 273 K)
nO2 = 0.0142 mol

Since the balanced equation will have integer coefficients, the moles of oxygen used should be a multiple of the stoichiometric coefficient in the balanced equation. In this case, since the moles of oxygen used are not exactly a multiple of 0.0142 mol, we can multiply by a factor to obtain an integer value.

nO2 = 0.0142 mol * (10/0.0142) = 10 mol (approximately)

Next, let's examine the change in volume when the excess oxygen is removed:

The volume of the remaining gases is 0.36 L, which consists of the gaseous products only since the excess oxygen has been removed.

Now, let's consider the volume reduction when the gases are bubbled through NaOH:

The volume is reduced by half, which gives 0.18 L.

To determine the balanced equation, we can compare the volume ratios of the reactants and products.

From the balanced equation,
1 volume of X reacts with a certain number of volumes of O2 to produce a certain number of volumes of products.

Using the given volumes, we can express this relationship as:
1 volume of X : 0.35 L of O2 : 0.44 L of products

The volume of X is 0.03 L, which is one-ninth the volume of O2 used. Therefore, the balanced equation would be:
1 X + 9 O2 → products

To identify the hydrocarbon X in the equation, we need additional information about its composition or properties.