Answer: (a)
Only statement 1 is correct.
Indo-Pacific Economic Framework (IPEF)
• It is a US-led initiative that aims to strengthen economic partnership among participating countries to enhance resilience, sustainability, inclusiveness, economic growth, fairness, and competitiveness in the Indo-Pacific region.
• It was launched in 2021 with a dozen initial partners who together represent 40% of the world GDP.
• It is NOT a Free Trade Agreement (FTA) but allows members to negotiate the parts they want to.
• Currently, India and 13 countries located in the Pacific Ocean are its members: Australia, Brunei, Fiji, India, Indonesia, Japan, South Korea, Malaysia, New Zealand, Philippines, Singapore, Thailand, United States, and Vietnam.

Answer: (a)
• The Indian Space Research Organisation (ISRO) has said its PSLV-C58/XPoSat mission has practically left zero debris in earth’s orbit.
About PSLV Orbital Experimental Module-3 (POEM-3)
• Launched on January 1, 2024, POEM-3 utilized the spent PS4 stage of the PSLV-C58 vehicle, which initially launched XPoSat.
• It is a three-axis-altitude controlled platform with power generation and tele-command & telemetry capabilities, for supporting Payloads.
• The XPoSat mission aimed to leave no debris in space, demonstrating ISRO’s commitment to responsible space practices.
• Upon deployment into its orbit at 650 km, POEM-3 was maneuvered to a 350 km circular orbit to minimize orbit decay time after the experiment’s completion.
• After completing 400 orbits, POEM-3 re-entered Earth’s atmosphere after 73 days in space.

Answer: (c)
Hydrogen, whether green or not, can be used in internal combustion engines, much like other fuels.
However, while hydrogen combustion in engines is technically possible, it’s less common than the use of hydrogen in fuel cells, primarily due to efficiency and emission considerations. Hence statement 1 is correct
Hydrogen can indeed be mixed with natural gas to create a blended fuel. This blended fuel can then be used in a similar manner to pure natural gas, including for heating purposes or for the generation of electricity. This is often seen as a transition strategy for decarbonizing natural gas grids. Hence statement 2 is correct
Green hydrogen is an excellent candidate for use in hydrogen fuel cells, which are devices that convert the chemical energy stored in hydrogen into electricity.
This electricity can then be used to power electric vehicles. Hence statement 3 is correct.

Answer: (b)
Revised Universal Soil Loss Equation (RUSLE) Methodology
• The Revised Universal Soil Loss Equation (RUSLE) is a widely used empirical model for estimating soil erosion rates.
• It is used to predict the average annual soil loss caused by sheet and rill erosion from specific field areas.
• The RUSLE methodology considers various factors that contribute to soil erosion, including rainfall, soil erodibility, slope length and steepness, vegetation cover, and conservation practices.

Answer: (b)
Statement 3 is not correct.
Dark Energy
• Edwin Hubble’s 1929 observations revealed the universe’s expansion, a discovery later complemented by the finding of accelerated expansion in the late 1990s.
• This accelerated expansion led to the hypothesis of “dark energy,” necessary to explain the observed phenomena.
• Dark energy is believed to exert a repulsive opposite to gravitational force that counteracts the attractive force of gravity between objects.
• This repulsive force is responsible for driving the accelerated expansion of the universe.
• The nature of dark energy remains largely unknown. It is often associated with Einstein’s cosmological constant, a term introduced into his equations of general relativity to allow for a static universe.
• However, its properties do not match those predicted by the cosmological constant.
• Note: Dark energy has not been directly detected in the laboratory or through astronomical observations. Its existence is inferred from its effects on the expansion of the universe and the distribution of galaxies.
• Everything we see – the planets, moons, massive galaxies – makes up less than 5% of the universe. About 27% is dark matter and 68% is dark energy.